I have a bit of a dilemma; I have 36K+ Starwood points and a planned trip to Vienna for three nights after a 20th anniversary cruise. I was originally planning to stay at a budget (i.e. Rick Steves style) hotel/pension then discovered I had enough points to stay three nights at either the Bristol or the Imperial.

Is it more prudent to save the points to convert to 50K airline miles (after a few more purchases) or burn the miles for a stay at either of these fine hotels?