The question has already been answered numerous times, but I wanted to add that making an endorsement into a flight review doesn't necessarily need to require any more time than just an endorsement.
As a pilot, I almost always combine a flight review with some kind of new training - whether it be endorsements, new ratings, or just learning a new airplane. Make it fun! I believe I've only had about two "regular" flight reviews in over 20 years.
As an instructor, any time I'm doing an endorsement or new aircraft checkout for someone, I ask if they want it to count as a flight review. It usually doesn't take any additional time at all. Remember, the main requirement for the ground part of a flight review is review of Part 91 operating rules.
As an example, last week I gave a checkout to someone in a turbocharged airplane. Well, a reasonable part of a checkout in a turbo is a review of oxygen rules, high-altitude operations, VFR cloud clearances above 10,000, speed limits, etc. That's all Part 91 stuff that I would be covering anyway, flight review or not. So to make it count as a flight review required no additional time at all.
If we go to another airport during the checkout/endorsement, I get to see their navigation skills and flight planning anyway, a normal part of a flight review ground and flight portion. We're going to do maneuvers and emergencies anyway as well, also standard flight review stuff.
Any thorough endorsement or checkout is going to have at least an hour on the ground and is usually going to at least touch on something in Part 91. So it's a simple matter of making it a flight review, as long as the CFI knows ahead of time!