Thanks to all who thanked me earlier in the post.
In your search, as Daboo said, try searchtempest.com. Searches craigslist over any size area you choose.
Since the discussion has slid towards a 400cc machine, don't forget the Yamaha Majesty. Personally, I still thought the B400 was quicker and more comfortable, but your GF might think differently. If I were to buy a maxi based solely on looks, I would pick the Majesty immediately.
If you are looking at the B400, they had a major re-design for the 2007 model year. The extra HP is offset by extra weight, but there is a MAJOR difference in the maintenance schedule, particularly valve checks. For that reason alone I would avoid the earlier models. If buying a 2007, check carefully for any noise from the clutch. Suzuki redesigned the clutch in later model years, but won't admit any fault or replace parts under warranty. I would focus on '08, '09, '10 models.
Somewhere amongst the posts there was a figure on the weight diff between a SW and a B400 - 150 pounds. Here are some more accurate figures:
http://www.bikez.com/motorcycles/honda_silver_wing_2003.php
http://www.bikez.com/motorcycles/suzuki_burgman_400_2008.php
http://www.bikez.com/motorcycles/suzuki_burgman_650_2008.php
Weights are 439 pounds for the B400, 481 for SW, 518 for B650. I believe all weights are dry. The weight for the 2008 SW shows 540 pounds, but I think it is showing the wet weight. My service manual for the 2003 model specifies 485 dry and 527 wet for the non-ABS model. I can't think of any changes in the bike to warrant the big weight increase except that the Bikez website posted a wet weight instead of dry for the 2008 model year.
All three bikes are listed as having lengths between 89.0 and 89.6 inches.
When choosing my scoot, I rationalized the SW as being only a little heavier than the small ones, but having the engine of the largest one.
Besides, the SW has that cool twin cylinder sound. The 400's have the chug chug chug sound of a single. It's just not the same music to my ears.
To anyone who thinks the extra performance of the SW engine is insignificant, I suggest you try a J Costa variator or lighter rollers. The JC will take the 0-60 time from 8+ seconds to the low 6's. It can't be beat. I can stay with my neighbor on his 1300cc Yamaha cruiser (water cooled and fuel injected 2009 model). I couldn't say that if my bike was stock.
Despite all the above info favoring the SW, any of the machines will give good performance and value. I doubt you would go wrong with any of them, but for a first time rider (and female) I would select SW first, B400 second, Majesty third and B650 last (too much weight mostly).