I'm just been using the preinstalled maps with my Garmin but have recently moved to Northern Utah where there are lots of mountains, forest service roads, and trails. I want to use the Garmin for tracking and planning hikes and rides both on and off road, though often away from cellular service. Which map sets make sense? They ain't cheap! The Topo 100K comes installed and has roads and such, and even shows some trails, but lacks any kind of routing ability. I think I would get this with the Topo 24K or the City Navigator. I'm not terribly happy with the breakdown of the maps. Does anyone know if it is possible to mix and match the maps, like load 24K Topo for Utah, Idaho, and Wyoming, which come in different map sets? I've heard you're better off getting the DVD than the MicroSD card. I guess they'd be way too big for download. Honestly, I haven't used the Montana much since the area I used to live basically sucked for doing anything outside. Now that I'm in a great area I'm trying to get up to speed not just on the Montana but on various mapping software and apps for all of this.