Especially for a beginner, seat height is definitely something you should consider when looking at motorcycles. Starting out, I would suggest you get something that you can easily have both feet at least mostly planted on the ground at the same time. Tippy toes is not optimal especially with a heavy bike, after coming to a stop and leaning the bike it can gain momentum toward the ground if you don’t have most of your foot there to stop it you might drop the bike and catch yourself underneath.
As a general rule and within bike styles, smaller engine bikes tend to be a bit shorter, but seat height varies a lot between different styles of bikes.
Most cruiser motorcycles have seat heights in the range of 26-29 inches high, While standards typically range from 28-31 inches high. Sport bikes seats are normally a bit higher and range from about 30 inches to 33 inches. Dual Sport and Enduro motorcycles as a group have the highest seat height to accommodate the extra clearance they have for off road capabilities, and their seat height generally ranges from 31.5 inches and up.
Some motorcycles have a low seat option you can get from the factory, this usually involves fitting a different seat to the bike or decreasing the travel of the rear suspension
A good way to gauge whether or not a bike might be too high for you is to get your inseam measurement from your pants and remove about an inch and a half or two inches. For most beginners I’d recommend a rider with a 32 inch inseam to get a bike with a seat 30 inches high or lower. One you have more experience handling a motorcycle you can move on to larger and heavier bikes with higher seats.
Be careful of road grade, indentations & potholesWhen you come to a stop be aware that a grade in the road or a pothole where you put your foot down may cause the bike to lean more than normal, or your foot not to hit the ground when you anticipate. View the two images below, see in the second one there is a downward grade to the left side. There is a greater degree toward the ground on the left hand side and consequently the ground is further away. Thus the bike will fall further before you’re able to get your foot on the ground. Also, your bike will gather more momentum toward the ground and also be heavier to hold up since it is leaning more. These images are exaggerated a bit, but I’ve found that even a slight unanticipated grade or indentation in the road can throw off your balance a bit if you’re not anticipating it.
Note that while many Dual Sport and Enduro bikes have a very high seat height, their long suspension tends to sink down a bit with your weight, so the actual seat height when on the bike could be a half inch or more less than the spec sheet says.