OP - were you trying to save enough points for your Doubletree stay or want to earn starting there?
I agree that a cash back or generic travel card may be better for many (and I have those, too), but I have found I get a good value with my Hilton Honors Surpass American Express. This one has an annual fee ($75), but pays better point rewards (12 per dollar for Hilton stays). I typically calculate it before I do the annual fee every year, and I usually far exceed the cost of the card to get extra value of points. You would need to travel enough, and choose Hilton properties enough to make this math work, though. I find there are usually plenty of Hilton options wherever I am headed, that it is easy to use this chain. There is decent consistency. Higher level Honors status gets a few perks (wifi, executive level, breakfast, extra points), and those do seem to be consistently delivered. Have stayed lots of places free, from quick overnights on road trips to a week at great places such as the Hilton Waikoloa in Hawaii. Some locales don't have quite what we need for a Hilton property, so we stay elsewhere (fairly loyal, but not exclusive customers).
My basic earning strategies:
-Signing bonus Surpass Card (current 60K points, but have to charge $3K in 3 months, one per account "ever" as I understand it)
-Each stay gets 500 point American Express co-brand bonus if reserve and pay on Amex Card
-VIP level bonus depends on your status and type property (example 250 per stay at Hampton, 1000 at Doubletree)
-Extra base points per level (25% for Gold, 50% diamond)
-Periodic bonuses, usually per quarter, offers change (maybe extra for weekends, or multiple during a time frame)
-Can choose points + miles with air partners, I choose points + points (50% extra base)
-Some types expenses earn extra: Hilton stays 12pts/$ (good), groceries/gas/restaurants 6pts/$ (fair) - note this is not %, is somewhat less for that
My basic spending strategies:
-There are sometimes wildly different "values" depend on property, each room point price has to be calculated for value. Have heard that Hilton values each point around 3-4 cents, but it is possible to get rooms with a point value closer to (and occasionally over) $1. This is when I choose to spend the points. If spending points will only get that low rate value, I spend $ which earns more points to use when the deal is better (especially if a good quarterly bonus offer is in the calculation). Example, I won't typically spend 50K points on a Hampton room, but might be a good deal for a Hilton on the beach (and sometimes have to include what else you don't have to pay, example may not have to pay resort fee if is a reward stay). Low end example: have booked 2 Hamptons for road trip to/from Disney (can't drive there in one day), each only 10K points. We've stayed in these specific hotels before, and Tripdadvisor rings no alarms, so should be excellent deal (by Hilton valuation, is equivalent of $40-ish, but I usually value points higher, so I feel I'm spending $60-70ish), both prices better than the $100+ they wanted for cash stay.
-Can also get better point rate if stay longer (think the cut-off is 4 days)
-Sometimes can get "specialty" rooms for good rate, occasionally better than standard
-Sometimes there is a special offer that makes paying with $ better (Amex card $)
Hmm, that got to be probably to much... basically, I find it works for me, and I like it. Sounds complicated, but is not for me now. Easy after understood structure, and I do kind of enjoy calculating the values (some would definitely call that work). I can see how/why others like other chains and reward structures. To each his/her own.
OP - even if you don't earn enough points to pay for your Doubletree stay, if you end up staying there anyway, I recommend get at least whatever points you can for the stay. I suspect you can squeeze out at least a free night somewhere with little effort.