shootinnews, I think you have opened Pandora's Box with your question. There are as many ways to approach your "concerns" as there are people with scanners. I think that imagination coupled with the capability of the hardware you have access to will have the ability to give you what you are looking for.
Unlike bchris, I have two Uniden BC780XLTs, but like bchris, they have been stalwart workers for me. It is really too bad that they won't be able to travel into the new age of coming things. As bchris has pointed out, there are many shortcomings with the 780s created by the HUGE number of UCAN sites.
I am basically stationary, being partially disabled, so I have my 780s programmed one site per bank. There are 10 banks with 50 frequencies and 100 TGs allowed per bank. I have dedicated each bank to a separate site programming in ALL the frequencies used by that site (Some sites rotate CCs like the AC33 system and the Airport TRS so there are many CCs. Why take a chance if the CC should be moved?) and all the TGs that site handles that I'm interested in plus those TGs that will routinely affiliate with that site such as the LZ TGs. The UCAN SL County site 003 is so large in the amount of TGs that will hit it that I have two banks dedicated to it. Ya, there is, by default, a lot of duplication, i.e. the LZ TGs are in every bank as well as the UCAN Engineers.
More than one trunking system can be programed into each bank, but (and this is the BIG "BUT") only one TRS can be active at a time per bank. You can, however, mix conventional frequencies in with a trunking system in each bank and they will be scanned.
I have sites 001 (Weber County), 002 (Davis County), 003 (Salt Lake County), 011 (Nelson Peak), SLC (AC33) site 01 (SLC PD, FD, & some airport TGs), and the Airport's site along with stragglers such as Murray PD which uses 800 MHz frequencies albeit in a conventional way rather than being trunked. With my 780s set up like this I have been able to copy traffic from Cache Co SO, Box Elder SO, Weber County including Ogden, Davis County, Summit and Wasatch Counties, Morgan County, North Utah County, Tooele County all the way to Wendover, and, of course, Salt Lake County which I feel pretty darned good about seeing as how I'm stationary, using the approx 2 1/2 foot, OEM telescoping antennas that came with the scanners, and from inside my house.
But now to your situation, shootinnews. I would advise you to purchase a "new age" portable scanner such as the GRE PSR 500 or one of the new Uniden models. Yeah, they're pricey, but oh, so dynamic. You are pretty well only limited by the size of the memory in the unit. With a GRE PSR 500, for instance, you can program (downloaded directly from the Db using software and your computer...soooo easy) a grundle of CCs and the scanner will do the rest. By installing "Wild Card" scanning objects, you are not limited to any particular number of TGs to listen to. You can also cross-associate scan lists. You can dedicate scan lists to geographical areas. The possibilities are endless, only limited, again, by memory usage and your imagination...and with the changes coming you will be able to use a "new age" scanner well into the future. Many of the "older" models are capable of being flashed for the rebanding changes, but many of them do not have the dynamic capabilities of the newest models to hit the shelves. Another thing to consider is that the current generation of scanners most generally will be digital capable as well.