I agree about the Guzzi horsepower. Those that say it is under powered likely are comparing it to a 1000 cc sport bike or something, and are disappointed that it wont do power wheelies at 150 mph.
A Monster would be a fun bike, but the Ducati requires quite frequent maintenance. I love the Street Triple, but that's a big jump from the 250.
I love my Aprilia Dorsoduro 750, which is almost the same bike as the Aprilia Shiver. The Apes don't have a very long range fuel tank (~120 miles), but maybe that isn't a problem for you. Maintenance intervals are longer than Ducati, yet they have torquey Italian v-twin motors
. What would make them nice for a first full size bike, though, is the adjustable throttle mapping. With the push of a button, you can dial back the power to "Rain" mode. I use "Tour" mode, and "Sport" mode makes it a twitchy race bike.
Definitely go to an international bike show. You will quickly figure out what is comfortable and looks good, while also getting the chance to see bikes you wouldn't necessarily find in showrooms. You've got one coming up in late January: