If you can find a hotel chain that your are normally pleased with, it makes sense to use them as much as possible in your planning. As long as they are consistent and they typically offer the type of accomodations and amenities that you demand, using one group of hotels or a particular member of a chain makes securing reservations fast and easy (one-stop calling) and you can be reasonably confident that all will be fine during your stay. Many chains also have incentive programs that you can maximize if you use them constantly. We have been Hilton Honors members for many years and typically prefer Hampton Inns when we travel in the United States. We have found them remarkably consistent over time and have almost always been very satisfied. We are actually planning a cross country trip this summer in which we will use Hampton Inns for about 90% of our stays. The hotels are reasonable in price and are found throughout the US.
Traveling overseas is a bit tougher. There are chains but they may not be as well known to Americans. The first time we traveled extensively to Europe, we used Best Westerns, but that chain is a bit more tricky, since each hotel is privately owned and thus varies from place to place depending on the owner.
Marriott is a pretty good bet worldwide, since they have hotels everywhere and maintain high standards. However they may more expensive than other chains, if budget is a consideration.