One thing you may want to consider if you ever plan on working with longer lengths of lumber, or doing a lot of rough cutting... is a front porch the same height as your doors threshold so you can put your saw outside.
In the same breath... put in an industrial exhaust fan. If it isn't super cold, have that thing going while you are in the shop. Your lungs will thank you, and your shop won't get as dusty. Plan on your heater, if you aren't using strip heat or infrared... try and get a propane one that can go up in a corner out of the way. Kerosene works well, but in the summer time you want to kick the heater out of the work shop... when winter rolls around you have to find it, dig it out... and you've lost an hour of work time.
I'd also think about some vertical plywood storage built in behind your work bench by the door. Put in some 2x4 runners to keep it off the floor, in case the door ever leaks. You can get much better pricing by buying 10 or 20 count of what you use, than if you buy piecemeal... Just have to have room to store it. You can get a sheet of sanded cabinet grade birch 1/2 inch plywood for 18 bucks... So, skin the inside of your shop with it and store the rest for projects. But you'll need 20 to get that price.
Also think about using your wall space over the benches to store lengths of lumber. A 1 foot overhang isn't enough to keep the weather off it. If its on the North side it'll stay damp, if it is on the south side it'll warp and twist... Unless you want to box in the area under the eaves to keep blowing rain off it, you'll need to stick every layer and plane it all before you use it as it'll weather outside.
2x4's about 2 feet long cocked up just a bit screwed to the studs works quite well. If your head isn't occupying that space, you can use it for storage... Put a layer of cheap stuff down first to keep everything else straight. Your rafters work well too, box in between 3 rafters and take a piece out of the middle one so you have an access hatch to get up there. Put plywood on both sides of the rafters in that area... otherwise you'll have to lift your board straight up between the rafters and then spin it 90 degrees for it to stay.
Think about some serious lighting. Depending if your height is 7 feet to the rafters or 8 feet, think about the slim line T12 bulbs and a lot of them. I would put in 3 rows, one in the middle... one half way to the door side, and the third directly above the work bench. Your work is only as accurate as you can see the marks....
Work bench wise... Make every top out of double thick 1/2 inch or 3/4 so you can use screws right into the top to make jigs and fixtures. Clamps suck when you can zip in a few screws and keep right on working. A layer of plastic sheeting (2-3 mil) will keep any glue from sticking your work to the bench, even epoxy... Zip in screws and you can run your router around... set the depth on the side of the piece you are working on... and it won't mar up the surface very much. I like to epoxy coat the tops of the benches and make them out of pretty decent plywood so it is easy to loft lines and such right on the top... But OSB board works great too. Use short screws for the top layer so you can pull it up and throw down another sheet...
Block in solid a section for your vice, and to bolt down a bench grinder to sharpen your tools... A bench grinder that walks is no good for the edge of your chisel... And a vice that isn't locked down is a fancy anvil...
Think about a 3 foot deep bench at the back wall like you have drawn, and a 2 foot wide bench going the entire length of the back wall. The 2 foot bench would be mounted at the same height as the table saw and other tools. Keep this one absolutely clean, otherwise you'll need a shovel every time you want to turn on the saw. I build a rectangle out of 2x4's however long, skin the top and then line up each end with a stud. Run a diagonal and screw it to the stud, and the frame of the top. 3 screws per upright. Now your table doesn't have legs so you can store stuff under it that is big... and if it needs to come out for a bigger project, you can kick it to the curb in 30 minutes. See if your drill press will get down to the height of your table saw, so you can dowel, or make plugs, and put it in the corner toward the end. Leave it far enough out of the corner that you can pull it out a foot or two and be at the doorway. (2 or 3 feet from the corner...)
Think about if you are going to use a chop saw, and make a drop down in the 2 foot table that can be easily taken out for its use... Use the table on the drill press as your outfeed side.
I like the 3 foot work bench to be 40-42 inches finished in height so you can work all day and not hurt your back from stooping. I'm 6'1... and that is the right height for anything laid flat on the bench. If I need to do something taller, I drag over a pallet... The 3 foot work bench means you can store things on the top of the bench at the back. I would make one corner a cabinet floor to ceiling. The top section being just for home made jigs and fixtures that otherwise pile up and destroyed when their use is forgotten. Put in cabinets above your head height the whole way across the top of the bench, and hang some serious lights under them. If you paint nothing else, paint this alcove white...
(Number the jigs, and have a note book that never leaves that shelf with what they are used for... and what model number door hinge that router jig is meant for...)
My favorite style work bench is a 5 foot by 9 foot table, with storage for full sheets of plywood on shelves inside it... and boards 10 to 11 feet long. If your saw has a motor hung out the back, you'll need a drop in spacer between it and the table, thats where you get the 10-11 feet. 4x4 posts with no uprights in between them. Make a frame on the inside at floor height and put 3/4 plywood there, put in 2 shelves, one real close to the top for 1/8th and 1/4 inch plywood with fine veneers. 2x6's to frame in the table top so it stays flat. Rip or joint one edge true. Use this with the 3 foot bench, and don't make the 2 footer down the side... Build a cart for your table saw to ride in, and bring the height of this bench up to 38 to 40 inches.
With that bench you have 3 1/2 to 4 feet on both sides in your 12 foot width, which is plenty to walk around if you are working solo.
That bench means one man can rip or cross cut a full sheet of plywood. Put the bench offset to one side of the shop, so your fence extension on the saw hangs towards the wall... you can pull your boards and plywood out from any side.
Also, don't get a router table. Get a table saw wing that works like one. Bench Dog makes them. Get a 2 1/4 horsepower router, and an aluminum drop in plate and you'll be able to do stuff on the verge of a shaper.
Power wise... Put in a plug every 4 feet, and run 240 volt power out there. Pull wire under the shop and bring it up to your middle work bench... for your saws and stuff so you aren't tripping over extension cords.
Air compressor wise... You'll hate the spiral cord for most things. Get a good year hose from harbor freight when they go on sale. A 25 footer, and one long enough to get out to the driveway to air up your tires.
Cheers,
Zach