I have been faced with this dilemma recently on several occasions and I was wondering what others do.

I usually try and get the most miles in any given account with the idea I'll use them for something someday. I don't fly enough for business anymore to get status (on any airline) so I try and maximize miles from personal trip expenses and non-flying accrual methods.

CO vs. NW

After reading both of these forums there are usually a fair number of bonuses being given if you sign up for them. I am a member of both OP and WP. I have more miles in WP but more flexibility flying CO (from IAH) If I have CO flight credited to WP then I lose out on CO bonuses and vice versa(NW flights credited to OP). What do other FT members do? Could apply to DL and UA too.

HP
I joined Flight Fund recently because I had 2 stays in Vegas. One at Mandalay and the other at Luxor. Recently they started giving Flightfund miles there (350 and 250 respectively). I probably wouldn't have joined FlightFund but I hated to lose out on something (even though some might argue it has minimal benefit if I never use it again.) Now I might need to fly HP for business and could get bonus miles in that account if I credit it there but just flight miles if I credit to CO (before that partership ends).

Do you take the credit as a partner in a program you favor or go for miles + bonuses in a new program you might rarely use?

Sort of like a short-term vs long-term investment decision.

Eventually, provided you keep the accounts current by earning once in 3 years and no-one goes bankrupt - you will get the miles up to a redemption level so taking advatage of lucrative bonuses is worth it in my view.

It also helps to have a few mileage options, that way you feel like you are getting somewhere when you pick up a cheap HP flight for a holiday rather than paying $100 more to fly CO or NW because you are trying to concentrate your miles.

However, the bonus has to be significant and worth the time and effort of having low mileage accounts hanging around.