I always found PC-DOS to be a great dos option for the 1000 line and would highly recommend it. I no longer have any 1000's (the original TL was my personal favorite), and never tried PC-DOS 2000 on it, but I assume it would be the best choice. The last version I used on any 1000 was PC-DOS 7 (and PC-DOS 2000 is PC-DOS 7 with some extras that you might not be able to use on a 286), and that was on an HX. As for a GUI, I would absolutely recommend Geoworks. It's hands down the best GUI for 88/86, 186, and 286's you can find. Not a lot of 3rd party software for it, but the native DTP, and office apps are truly a thing of beauty of for their time and can still get the job done today.
Just for the heck of it back in '92-93 I built up a SL, with Cyrix 8087 math co (back when Cyrix was good), oak VGA, paper white VGA monitor, Apple IIe on a ISA card for PC's, (which would only work with built in video and not the VGA board so that was a bit of a pain to switch back and forth), RLL card with two 40MB MFM drives that I connected up and low level formatted with 1:1 interleave to 60MB each on the RLL board using DR-DOS 5 or 6 (which had some extras for Geoworks), and a few other odds and ends. It really was a very useful little machine and I ended up selling it for about $1000 to a local psychiatrist for her receptionist to use as the office workstation. Getting an LED printer working with it was a bit of a hassle though and she needed reasonable output. The IIe was something else she needed as that's what she was using for 5-6 years before. All in all, it turned out to be a fantastic little rig that was a really good value for a little old 8086 and at a time when most were going to higher end 486's. Those old Tandy's are great little boxes if you know how to work them. Getting HD floppy drives working isn't to hard, but requires a bit of re-wiring the molex's.
Personally, just loved the TL with a HDD that I would format to Tandy MS-DOS 3.2 or 3.3 (cant remember which version was on ROM), and then boot from ROM. Tandy 1000's with DOS in ROM are still the fastest booting x86's in the world today. Press button, and one second later you were at the prompt MS-DOS prompt. Truly awesome.