You might be visiting a friend who lives far away from a decent wine shop, or live in an area without shops which stock smaller, higher quality houses and grower champagnes. If that is the case, try one of these 3 champanskoyas:
Bollinger Brut Reserve NV - Depending on where you live and how liberally the local bottle shop marks up champagne, this will probably run $38 - $52. As always, it is big, rather austere and with a good base of tangy red berry fruits from the Pinot Noir. I am always happy to drink Bolli.
Pol Roger NV - $30-$45. This is not particularly exciting in my book, but always tastes clean and has the perfect amount of toastiness to add a bit of richness and texture, which balances the bright appley and lemony tones.
Laurent Perrier NV - This is a very distant 3rd pick, just because it will be available, probably cheap ($28-$40) and won't offend anyone.
Once again, this list is based on a shitty neighborhood shop selection (though I really do enjoy the Bolli). If possible, you should find Champagne elsewhere and get the really good stuff.