Hey ams, don't know if you've ever been on the thortrains.net website, but there's a lot of good info, as well as layout ideas.
I went through the 027 layout pages. Some of them have 3D illustrations to help you visualize a completed layout. There are none of these pages for 4x8 layouts, but there are some for 4x6 layouts. Take a look... you could easily lengthen anyone of these to 8 feet long. But I thought these might inspire your creative process.
I wouldn't worry too much about short sidings. On a smaller layout, those are just a given. But visualizing inadvance what sorts of accessories you'd like to have on your layout will help you determine how much space you need to have around the track sidings.
Hope these give you some more inspiration. And good luck... have some fun!
http://www.thortrains.net/marx/460271.html
http://www.thortrains.net/marx/460272.html
I'm a 027 guy. Some tips I did on my layout. I made extra ties from brown hobby foam like you can get at Hobby Lobby. I cut them myself to the size of the upper part of the tie. When you consider the bend at the bottom of each metal tie, the size becomes bigger. I used an ordinary glue stick to help hold the ties in place. They do a great job in helping to reduce the "rumble" noise of the trains on a board. I also used self-adhesive insulation foam on the bottom of each metal tie of the Lionel 027 track.
I use manual switch tracks because I'm not a big fan of the non-derail feature on 027 tracks that derive there power from the track. I know you can rewire the switches to auxiliary power, but I went with manual switches. For places harder to reach, you can use ordinary nylon fishline to rig up a simple control of the more modern MPC-era design switch tracks.
I have rewired my uncoupling tracks to work, not from track power, but from auxiliary power, which I would recommend doing. That way, your UC action is always the same, regardless of how fast or slow the train is running.