First of all, what on earth is a blend and what's a varietal?
A blend is a wine, red or white, made of several different grape types. A varietal is a wine made entirely or almost entirely of one single grape -- one variety, hence "varietal." As author Karen MacNeil points out in The Wine Bible, until the 1960s most people had never heard of the actual grape varieties, like chardonnay or cabernet sauvingnon. Wine making was a European tradition and European wines were very often blends of grapes, the wines themselves named after the places they were made. Champagne, Chianti, and Bordeaux are all places.
When California and other "New World" winemakers got started making serious amounts of serious wine, they made and labeled their product after the grape type, for two reasons. First, because they were working with the noble grapes that Europeans had always used, and they wanted people to know that. Second, because California, Australia, South Africa, and South America didn't and don't have the centuries of wine making traditions behind them which help buyers instantly anticipate what "a Napa" or "a Victoria" will taste like.
Now, European winemakers are beginning to put varietal names on their labels, too, as a kind of backup I.D., perhaps because they realize the American wine market has learned to buy and drink according to grape type, not necessarily place of origin. This backup labeling works especially for the European wines, and there are some, that have traditionally always been made from one varietal anyway. White wines from the French province of Burgundy, for example, have always been chardonnays. Red wines from Burgundy are pinot noirs. A Vouvray (it's a town) will be made from chenin blanc grapes.
If you want a blend, therefore, you might try one of the French, Italian, or Spanish wines that have typically been blends. Bordeaux, Chiantis, Rhone wines, and Spanish riojas fit the bill. Of course, American, Australian, and South African wines can also all be made as blends, too, not least because New World winemakers want to try their hand at blending the grapes that have made exquisite wines in Europe for centuries. If you buy a glass of, say, a cabernet-sauvignon/merlot blend from Chile, you'll know that the winemaker is recreating the blend that is Bordeaux. But a European -- or New World -- wine that carries a place name, not a varietal name, will likely be your blend.
What's the difference in taste? Blends, especially blended reds, can be a bit softer and smoother than the single-variety wines. Some pure cabernet sauvignons, especially, are what Hugh Johnson calls "turbo-powered" -- dark, astringent, high in alcohol, and not necessarily what we are looking for as we start our adventure.