Warning!! Wall of text ahead!! Sorry. I started this for selfish reasons. Since I put a considerable amount of work into these ships (though not nearly as much as Luke83), I thought I should share what I've done. I triple checked my work to make sure it was complete, though it's still possible I missed something. I hope my efforts are appreciated.
Since I am too scatterbrained to focus on creating a new layout from a hollowed out ship or from scratch, I simply modified Luke83's existing layouts from his latest version (that I could find) to (in my mind) better represent the alien's purpose for building them. I tried to keep the feel I thought he was going for with each design, but also tried to keep in mind that the aliens don't want their leaders to fall quickly in a seige, so I made sure the bridge isn't always easy to assault (but there are always improvised shortcuts!).
I used the vanilla ships for most of my answers when I had questions and I wanted to keep true to the vanilla ships in terms of loot. Alien alloys aside, I tried to make sure each ship has the same number of power sources, alien food canisters, alien entertainment, and UFO navigations as vanilla, though an extra UFO nav might still appear occasionally. (Some had a LOT more, I thought it unbalanced, but a few more here and there can be fun.)
@Luke83: I made a few interesting layout changes, complete with new routes. I hope you don't mind but I took a few liberties here and there. I also named mine differently so I could compare them to yours (I just removed the O from UFO for my purposes). I included my MapEdit.dat so you can compare my versions with yours also, if you wish. I'd be very interested to hear your take on my alterations.
What I did:
Gave most ships roof patrol paths for flyers.
Harvester interiors were overhauled to better accommodate flyers.
Abductor interiors were overhauled to prevent easy bridge access.
Terror Ships were made to be very scary and not to be trifled with.
The first zip is for Luke83 and has my name changed files with MapEdit.dat included that references both versions, the second zip is for everyone else and has all of Luke's ships that I've updated and uses a slightly doctored version of Luke83's ruleset with a few fixes (terror ships 7 & 8 should be ignored for now until they are working) and uses all the original file names for consistency.
Included and working: all 11 12 Lg Scouts, all 11 Harvesters, all 10 Abductors, 6/8 all 8 Terror Ships, and 2 4 Supply Ships (I basically just rotated it so that there are two possible orientations for the vanilla version and implemented Solarius Scorch's loading door). I haven't made any new layouts for that last one. Probably won't, either. I didn't touch his Medium Scouts, so you'll have to download his original mod for those files.
Luke83 originally made this fantastically groovy mod. I just played with it to get it to work for my purposes and since I had the time and cleverness to figure out MapEdit. I hope everybody knows how to install these and how to back stuff up. Just make sure to unzip the data folder into the openxcom folder and you should be fine.
Edit: I missed one thing on a terror ship. There was a door in a wall that didn't show up in the Map Editor but was visible in-game. Updated my files with the fix.
Edit2: I got those last two terror ships working. Also includes 2 more Supply Ships with the 3-wide loading doors (Thanks to the idea from Solarius Scorch).
Edit3: Last Update! I made sure those aliens know what's good for them in their own ships. Also found an extra Lg Scout.