Two cruisers can measure almost the same on a spec sheet and ride nothing alike. One feels unhurried, planted, a little lazy on the pedals, and you come back from a mile on the boardwalk without thinking about the bike at all. The other feels faster in the first hundred feet, then starts complaining: a wrist that goes numb, a knee that tracks oddly, a stop where you tip toward the curb instead of standing over the frame. Almost all of that difference is fit, and almost all of it is checkable standing still in the shop.
Standover, and the check that takes ten seconds
Straddle the top tube in the shoes you will actually ride in, feet flat, and look down. On a step-through frame there is nothing to clear and the question is moot, which is a large part of why step-throughs sell. On a diamond frame you want daylight, roughly an inch or two, between you and the tube when both feet are on the ground. Less than that and every stop becomes a calculation. The Consumer Product Safety Commission oversees the safety requirements bicycles must meet before they are sold here, but nothing in that remit decides whether a particular frame clears your inseam. That part is on you, in the store.
Saddle height is a trade, and you should know which side you took
The efficient saddle height, the one where your leg comes close to straight at the bottom of the stroke with a slight bend at the knee, is usually higher than the height at which you can put a foot down without leaving the saddle. Riders who plan on frequent stops, sand-blown paths, crosswalks, dogs on long leads, tend to drop the saddle an inch or two below that mark and accept the loss. The bike then feels slower, because it is. You are pedaling with a knee that never fully opens, so each stroke does less. That is a defensible choice for short flat rides, but make it deliberately rather than discovering it on a hill.
A useful compromise many people never try: leave the saddle at the efficient height and practice sliding forward off the nose to a foot down, which is how road riders have always stopped. On a cruiser with a wide sprung saddle that slide is less pleasant, which is why the low-saddle habit persists. Test both in the parking lot. Ride a loop with the saddle where the shop set it, then raise it three quarters of an inch and ride the same loop. The difference in how hard you have to push is immediate and obvious.
Handlebar sweep decides where your wrists end up
Sweep is how far back the bar bends toward you from the stem, and cruiser bars run anywhere from mild to the deep swept-back shape that puts your hands beside your hips. More sweep puts the wrist in a more neutral position, thumbs up rather than rotated flat, which is the single most common cure for hands that go pins-and-needles after twenty minutes. It also shortens your reach, sits you more upright, and moves weight onto the saddle and off the palms. Check the angle of your forearm and the back of your hand: they should make a straight line, not a bend.
Why a laid-back seat tube changes what your legs can do
Cruisers put the seat tube at a shallow angle, so the saddle sits well behind the crank rather than above it. That is what produces the long, relaxed, feet-forward position people buy these bikes for. The cost is leverage. With your hips that far back you push the pedals forward more than down, so you cannot stand and stomp effectively, and starts from a dead stop take a beat longer. On flat ground at a walking-plus pace, none of that matters much. On any real grade it matters a lot, and a slightly steeper frame, or a saddle pushed forward on its rails, buys back some of it.
Bring the two bikes you are deciding between out to the same stretch of pavement, ride each one twice, and change one thing between runs. Saddle height first, since it costs nothing and explains the most. If the slower-feeling bike is the one you stop worrying about after four minutes, that is your answer.