I guess I'm also in the majority -- "it depends". I went out solo many, many times the first few years that I chased, and I think it forced me to learn a lot about chasing (and basic meteor.) very quickly. After all, when you bust, there usually isn't anyone else to be blame but yourself. Similar to others, I like the idea of calling my own shots -- given the time and money involved, I'd like to know that I can only blame myself if I bust. In addition, I enjoy driving, and I guess I just don't get bored often. In addition, I find it much easier to go solo before storm-time, since driving home after a chase can get a little tiresome. Overall, though, I find my driving to be quite peaceful -- roll the windows down, turn up the radio, and check the data every 15 minutes so I can keep up-to-date
All that said, I do enjoy company, and some intelligent chaser-discussion can be beneficial when it comes to adding more opinions to the forecast process. In this regard, I've found a relatively small group of fellow chasers (who are also largely grad students and friends) with which I often share opinions and thoughts. Chasing with others is much easier if you all respect each others' opinions... I surely would have busted some days if I just did things "my way"; collaboration with others in my chase "group" has saved a couple of chases. Then again, it sometimes goes the other way (i.e. I should have stuck with my guns more), but that's just the way it goes. After the chase, it's nice to have some friends along with whom you can shoot the breeze. Heck, I've had some very odd post-chase discussions through the years, but it all helps the time pass. In addition, chasing with a small group certainly helps during those active periods, particularly when I'm down from persistent busts or disappointments. I've found that my motivation to chase solo is heavily influenced by recent activity... If I've anticipated the day in question, and I haven't had a string of bad days, I'm much more willing to go out solo. Conversely, if I've had several bad days in the recent past (e.g. 2-4 busts in the 7-10 days), I'm much less willing to head out if nobody else from my chase group can go out with me. Heck, at the end of the 2002 spring (a spring in which I seemed to cap bust repeatedly), I didn't even feel motivated to go out for later GOOD days. I guess that's just the psychology of this hobby.
Now that gas has worked its way to $3/ga, offsetting cost is nice as well. I really don't consider solo chasing if the target is >250 miles away. I'll swing a tank or two of gas for a solo chase, but much more and I'd really prefer to find at least one other person with whom I can split costs.
Most of my chases are single-day outtings (<1000 miles roundtrip), so I don't have a whole lot of experience with overnight hotel trips. I had a few this past spring and don't have any bad experiences (aside from a shady motel or two). I like to know personally the people with whom I chase, since I know that I won't be surprised by a "this is scary -- let's go back" or a "I know it's only 8pm, but I need to get housework done before tomorrow" line.