Like eveyone else, Sara, I'll tell you that it depends on what room you're eliminating. But it also depends on the type of house and its size currently, too. I've had a number of buyers this year eliminate a house from consideration because the formal dining room had been turned into a breakfast room, or the living room -- while little used -- had been converted. Their concerns were the resale value of the house in the future, as well as whether the house would met their needs in the future -- say, when their children are grown and gone, and they're doing a different style of entertaining.
On the other hand, clients of mine did a beautiful job of renovating their kitchen to include the space of the breakfast room, without losing a spot for informal dining. It opened up the entire area to work so much better and be so much brighter -- looks like it's right out of a magazine!
A service I provide (and I live in Ellicott City as well as sell there extensively) is to answer those what-if questions one-on-one. Please contact me so we can e-mail or chat further.