I have permanent Silver status with Hilton as long as I hold their AMEX card. Since it's a no annual fee card, that's a no-brainer.

If I run $20K a year through the card (also not that difficult -- man, I run everything through a credit card! ), I get Hilton Gold status. There's a rumor that spending $50K a year on the card gets you Diamond.

Not as nice, but certainly cheaper than buying a timeshare in Fiji.