Perhaps I'm dense but I'm having trouble understanding what you're saying...

Is this purely a financial calculation - where you are willing to pay a certain amount to get back some free stays, and overall you are positive $ on the deal?

Or is it a situation where you could choose to have someone pay for some (relatively cheap) stays and you want to maximize what you get back, regardless of if it's positive from a purely financial perspective?

If someone else is paying, and your only concern is to be "reasonable" in how expensive the hotels are - i.e. staying in Hampton/Fairfield Inn versus a full service hotel, then you can do well.

If redemption opportunities are most important, you should consider mixing several chains, changing hotels every night or two. Something like this would probably be best:

1) Stay at Fairfield Inns a few times for the quarterly MegaBonus - lately it has been Stay 2 times, get 1 free night, up to 2 free nights. Make sure to register using a 5k referral for new members.

2) Stay at Holiday Inn Express locations to reach whatever quarterly tier promotion you can find (something like a Stay 12 nights, Get 15k points) - while also maximizing all other promo codes. There should also be a new member referral bonus.

3) Go for whichever lower-tier program has a free night offer (Choice and Best Western usually have Stay 2 Get 1 Free offers)

Ideally, you'd want to use the hotel's own credit card to pay for the stays. If you were to sign up for the Priority Club Visa with at least 60k signup bonus, you'd start with Platinum status. The Marriott card will start you with Silver. You may also be able to convince Marriott to give you a Platinum challenge based on PC Platinum status. Then you could increase/renew elite levels incidentally as a by-product of staying.