If there's a real-estate bubble these days, folks who recently bought a fancy house are glad to pump it up more with home improvements. This emerges from the latest Coldwell Banker Luxury Index survey, fielded by International Communications Research among people who make at least $100,000 and have bought a home worth $1 million-plus in the past two years. Thirty-one percent of them said they plan to expand or remodel their homes in the next 12 months. Among the top projects planned for this year: topiary/landscaping (cited by 23 percent), home theater system/ room (13 percent), gourmet/designer kitchen (12 percent), hot tub (10 percent), in-ground pool (8 percent) and wine cellar (6 percent). You'll be relieved to hear that 64 percent said recent rises in interest rates will have no effect on their plans. By the way, why settle for just one home when you can have a pair of them? Seventeen percent of respondents plan to buy a second/vacation property this year, atop the 27 percent who've already got one.