For multi-band monitoring and/or trunking support, besides Uniden and RadioShack, you have the AOR AR8600MKIIB or Icom IC-R2500, PCR-2500 or IC-R9500. If you want a handheld scanner you're stuck with the two you mentioned though GRE has branched off on their own.
The commercial gear like trooperdude mentioned would work best for P25 but would require a little more effort and cash to program though many can be programmed from the front panel. Not the greatest scanners if you want to scan a lot though.
The ideal P25 receiver would be a Motorola radio with the newest DSP. The RadioShack/GRE scanners are pretty close in decoding quality.