If I left now, I would probably be in my late twenties upon the ship's return. It would be an adventure, an educational experience and as noted would look fantastic on my resume. While there might be dangers on the mission, I would want a reasonable expectation of a round trip.
Were the ship to have a crew the size of the Enterprise Dee, about a thousand people , there would be enough of a assemblage for me to acquire a nice circle of friends during the journey. But not so large that over the course of years I couldn't become acquainted with just about everyone.
And your life on a starship might be even more confining and limiting than the daily grind you have now. It might be like working in an office building you never get to step outside of.
Perhaps more like living in a small isolated town somewhere, or on a island community. At the speed the ships move in the various series, the time between star system would be measure in days. Depending upon what it is you do aboard, there would be opportunities to leave the ship for investigations, to explore, or simply to stretch your legs in a unique environment.
the solar systems you'd explore might all be lifeless
True, but if given the chance to just go to some place like Mars for a extended visit, then return to Earth, wouldn't you want too? Even knowing in advance that it's (probably) completely lifeless.