I own a Raleigh Port Townsend, which is basically a Raleigh Sojourn with cheaper components. I have used it exclusively for two years. For once in my life, I am an expert!
1. I replaced the seat immediately. The stock leather or synthetic-leather seat is not comfortable even after being broken in. Consider this in the cost.
2. At stoplights, the weight of the bike was noticeable. I commute in traffic, often taking the lane, but having a real difficulty getting the bike to lurch forward without any extra weight on it was not much fun, and was occasionally a real nuisance for cars. When I try out lighter bikes, this is when I most notice the difference.
3. Off-road, it's no mountain bike. Gravel and sand are pretty uncrossable, although really packed gravel is fine. It's a burly bike and you won't break it, but the thin tires make off-roading a real challenge.
4. I put on 3,500 miles just commuting, then I put on another 1,500 touring. the 1,500 was the most enjoyable- the bike was in it's element and the frame dampened most road buzz. It was very comfortable on long rides, once I passed the threshold of butt and back pain.
For your needs, I would actually look into a Cyclocross Bike.
The Raleigh RX-1 weighs 5 or 6 pounds less and has lighter rims. Since rims are subject to centrifugal force, the lightness here makes a HUGE difference at stoplights, or when starting from 0mph. This bike also has pretty burly tires for trails, and because it's built for off-roading, everything is burly enough to last you a while.
So yes, the Sojourn would probably be overkill, but once you get the "bug" of long trips, you might wish you had that indestructible steel frame and rack mounts...