As a current M20C owner ('65) I -highly- recommend them. I love the manual retracting landing gear- good ol' Johnson bar :3 Mine is in for it's annual right now.
I'm 5'11, 220#. Have flown with 3 other souls. With the front seats pushed all the way back it's very comfortable, but that means no adults in the back seats.
Sounds like your best bet is twin engine if you want to carry 4 or 6 plus luggage. Even then you'll have to leave some fuel behind (been there, done that). But twins cost so much more >_<
long as it has all it's certs you got yourself a nice commute craft there
--Rick
--Rick