I don't think it's fair to compare SPG Category 6 hotels with Hyatt Category 4 hotels. I think in general Hyatt Category 4 Hotels = ~SPG Categoy 4 (and sometimes Category 5 hotels). I would rate the Westin Maui and Hyatt Maui approximately the same. In that case, you need 10,000 SPG points and 15,000 GP points like the above poster pointed out. Yes, some of the Hyatt properties are exceptional (PHT) and it's possible to compare Hyatt Category 4 with SPG Category 5 (HR/GH Kauai vs. The Princeville).
In general I value a Hyatt point at ~1.25- 1.5 cents. I value an SPG point at ~ 1.9- 2.0 cents. So I figure an SPG point is worth ~50% more than a Hyatt point. You are correct when you say it is hard to earn Starwood points from stays. They are awfully stingy giving those things out for stays. However, it is easy to get them other ways (SPG Amex, Ameritrade, etc). I just signed up for a couple Ameritrade accounts and will be getting 40,000 SPG points ($800 I figure or 5 nights at Westin Maui or similar Cat. 4 property). Not bad. You really can't do that with Hyatt since basically the only way you can get Hyatt points is by staying at a Hyatt. And by staying at a Hyatt, you are correct that it is easier to earn GP points (G1/G2/G3, 6.5 points per $ spent, etc). I think the real draw to Hyatt is its liberal promos (like FFN, G1/G2/G3). And the customer service and experience in general at Hyatt and GP far surpasses that at Starwood. The Suite upgrades are nice at Starwood when you get one, and the fact that there are lots of Starwood hotels all over is also nice. I think you're going about it the right way. When you can, stay at Hyatt. If there is no Hyatt, or if Starwood has better offers/promos, stay at Starwood. And to get extra SPG points, definitely accumulate them in as many other ways as you can. Get the SPG Amex and USE IT as much as possible (it's basically like a 2% rebate in the form of hotel stays). Rephrase----> Use your SPG Amex as much as possible except for when you are using your M/C for FFN.
