We spend our summers in Summit County (Breck/Keystone/Copper) and it does take a few days to acclimate. I would recommend a night, perhaps 2 nights in Denver. Steamboat is at a lower elevation then Summit County, not sure the timeshares in Steamboat classify as luxury. If you are willing to spend a day or two at a lower elevation, there is a unique place in Beaver Creek. Poste Montane is a small timeshare that is 100% luxury, it feels like you have stepped into an old European hotel. Absolutely beautiful, not many trades, but I would stay there again in an instant. The resorts listed in prior posts Hyatt, Grand etc…are very nice - but with the exception of Hyatt - they are large resorts. Every person defines “luxury” differently - for me the Poste Montane was luxury, small, intimate, great service, staff knew our names and what we wanted for breakfast. Also you did not say WHAT you wanted to do on vacation. If you can budget for luxury, I would also recommend Telluride - that is separate conversation.