I'm pondering a similar question, though on a longer time span. I am absolutely in love with my Bridgestone RB-1 and plan to keep riding it as my main bike for years to come. I'm also having a lot of fun fixing up older lugged steel bikes for various uses or to sell. For the next few years, I'll stick with what I have, making a few upgrades here and there. But in 5 or 6 years I'll be retiring from the main gig and I want to reward myself with a new, high(ish) end bike. Something around 3 grand, give or take. Part of me wants to go for a custom Rivendell, and that may be just what I do. But another part of me wants to get a more modern, lightweight, go-fast bike.
Aluminum bikes are probably a good value, but I'm not interested. High quality steel, titanium and carbon are the things I'm considering. Steel is my sentimental favorite, but titanium has a lot going for it. Carbon is the dark horse. I'm not sure I could ever pull the trigger on spending big bucks for a plastic bike, long term durability and repairability being the main concern.