I've ridden with people using Garmin and Magellan and even tried my hand at data input with them (searches and such). Found them both to be more difficult to use for searches and data entry than my Tom Tom 720 (now it's been updated a bit, too). I've also been cautioned by people that I've visited that "Garmin won't get you to the house, so when it says you're at your destination, then do this for the next half mile or so:" Whassup with THAT?
Mine has lane assist, but something specific for you might not be available. It also supports real-time traffic updates and some other stuff, although I don't have that option.
I plug my 720 into the truck stereo and then plug the iPod and/or XM head into the GPS and connect it to my phone with Bluetooth, so everything goes through the GPS. If you're tripping to Sgt. Pepper and the GPS wants to tell you something, it mutes everything, tells you whatever and then resumes the music - does the same with the phone, and the phone can be dialed by voice. Outgoing phone audio is average, but incoming is very decent.
Just updated my USA maps - first time in 4 years - for something like $60 bucks.
gn