Reasonable comfort. Subjective, but I'll give it a shot. Two TOTALLY different bikes:
I own an SV650 that is really a lot of fun two-up. I haven't ever had a complaint from someone on the back. A harley rider said its the most comfortable bike she'd ever been on. SUPER light, but surprisingly well behaved even when it's loaded down. Decent power and enough brakes to make up for added weight.
And number two: The FJR 1300. Obviously plenty of power, totally linear and friendly. The non-compliance with what you're looking for is the heft. Not too noticeable when you're riding, except maybe on the brakes. Turns in pretty quick for a 600 plus pounder. And it inspires oodles of confidence.
You didn't say much about the distances you'd be riding. Trips on the SV never last more than about two hours, and at that point it's definitely break time. It's just so damn cheap
