Sights: There’s plenty of Champagne on offer with most of the big houses offering tours: Veuve Cliquot is classy with an interesting comparison tasting available; Taittinger is interesting as the cellars are in the ruins of a former abbey.
Epernay is a typical agricultural town (whose crop happens to be champagne) so I would stay in Reims and travel across to visit the main houses based there. Mercier is a household name in France but less known abroad and offers a good tour including an underground train ride, with up to three glass of fizz at the end.
The villages and countryside around are pretty, and include Hautevillers where Dom Perignon is buried. Going for a drive with a picnic is a nice way to spend an afternoon.
Travel: We took the tunnel and drove to Reims using the Autoroutes (about two and a half hours). French motorways are not cheap but save a lot of time and petrol. However, it is equally easy to fly or take the Eurostar to Paris and change to the TGV (fast train) to Reims (about an hour). Outside Reims, a car is really helpful to get out in to the hills and some of the more remote vineyards.
Accommodation: Best Western La Paix Reims (9 Rue Buirette): This is an excellent hotel with large, modern bathrooms and centrally located. Highly recommend. http://www.booking.com/hotel/fr/best-western-de-la-paix.html?aid=1222377&no_rooms=1&group_adults=1
Food & Drink: We enjoyed Le Wine Bar (16 Place du Forum) which had good wines from across France (& good snack boards) and Les Cornichons (13 Rue du Général Sarrail) which was a little more studenty with good beers & hearty meals. In Epernay, C Comme Champagne (8 Rue Gambetta) has a great selection of fizzes which is always changing as well as some light snacks. For something a bit different, the Perching Bar (faux de Verzy, 51380 Verzy) is a tree top Champagne Bar which has good views plus several local fizzes to try (www.perchingbar.eu).
Further Reading & Listening: