I know people will say, well, you don't tip less at a fancy restaurant just because the food costs more, but I have an ingrained opinion that well, if the parking at a W costs $25 per night, shouldn't the valet be included in that?
Just a rant...
No nearby parking garages? If you're in a medium sized city, you can park on the street for free in the evenings (read your signs carefully), or just find a garage or open lot that has a flat rate that costs a fraction. I never got why people always default to the parking garage located in the hotel, cept maybe a corporate write off or mobility issues.
Valet is nice, but so is saving $10-20 a night and putting it towards a case of beer/nice bottle of booze/really nice dinner/etc.