I have a Street Twin and it is amazing. Great on the highway, superb if a little big and heavy in the city. Works comfortably for long road trips too.
Mine sees the highway every day and I rarely get to open it up because of traffic. It will comfortably do 90mph when you feel like light hooliganing. While it can do 110mph and a little beyond, you can tell it isn't quite happy at that speed (or at least not comfortable).
Within the city it's great, but often feels like a struggle to drive slowly enough to match traffic. You can tell your bike is sad sitting in 2nd or 3rd gear at 30mph with 10% throttle. It's also pretty heavy so tight maneuvers between cars during gridlock traffic can be a challenge.
But with the vance&hines slip-ons (and baffles out) it's loud enough that standing traffic parts like the sea for you. it's beautiful to watch. Get blocked while filtering, don't even have to rev, just sit there for a few seconds and cars start moving out of the way. Love it
Longest trip I've done was from SF to Yosemite and it did great.
Oh and the mileage is amazing. I get around 60mpg in city traffic. Goes up to about 90mpg on long trips.
PS: if you're worried that it isn't enough bike for the freeway, just keep in mind that it will gladly go up to 50mph in first gear. It's plenty of bike ;)