It appears that I have to sign in to the BBS on a daily basis. This does not appear to be intentional, and it's certainly annoying. I believe in the previous version of the BBS we had a one month sign-in expiration.

My cookies seem to be in reasonable shape for expiration dates:

www.lexaloffle.com:
PHPSESSID: when browsing session ends
pass: one month
user: one month

lexaloffle.com without the www also sets a cookie, __cfduid, but this doesn't seem related. I have tried clearing and recreating all of these cookies, with no change of behavior.

I'm also getting logged out after a few hours of inactivity

This is fixed now -- was storing session data in the wrong place. :|