GPS is a good one! Is it just the 536, or do the others do it too? And about how much money for a GPS dongle that works? I'll probably add that to the list sometime soon.
Many Uniden models support GPS auto-programming, going back at least to the X96xt series. Possibly further, I'm not that familiar, not owning any of them. I priced the GPS puck awhile back, I want to say it was on the order of $70-$80 but I can't recall at the moment. I do know that a lot of Uniden users really like this function, especially with the HP-1/2 series.
I'd add my vote for Whistler to pick this function up, it would be a great addition. I have nothing against Uniden but I got back into scanning after a long hiatus (during which
everything changed) with a RS/GRE scanner, so that's what I'm used to. I'm looking at adding a Uniden scanner of some pedigree just for the GPS, since I'm contemplating doing a good bit more traveling in the next few years than I've done in the last couple of decades...I'd just as soon stick with what I know. After setting up a few X36hp's for friends and associates, I find Sentinel a little less user-friendly than iScan/E-Z Scan. Which is no reflection on Sentinel or Uniden, it's just different from what I'm familiar with.