Agreed with most of the above, but maybe not in the same way...
The Shebles are great folks, and it is a great place to do training. You just have to be realistic of your expectations going in. You simply can't go to the cheapest, fastest place and expect the most amount of training.
Notice I didn't say best. Quality is not the issue, you will get great training, but you are paying for their time, and not much of it. As far as diversity goes, I will say that the average SES candidate is going to depart on the CO River and fly straight to Lake Mead, the wind always blows at Lake Mead, that will make some things too easy, and others too hard...but it's also riddled with coves that will be glassy in the am. Then you will fly down the Colorado to lake Havasu, which is likely where you will do your check ride.
So as to diversity, I would say location is not the limiting factor here, but
time is. The whole shooting match is going to be a matter of a few hours. Just how proficient do you think you're going to be at anything in just a few hours? I did my SES there with the late Sean Sheble, and my ride with Joe LaPlaca, and the day I was doing my ride he had a gal doing hers as well. Gump may know the gal, this gal had a Caravan on amphibs waiting for her to return to at Lake Powell

And yes, she paid for more time
If you are a cub guy, you might get more out of training in the cub, because the 'cub' part of it will be second nature, so you can focus on the 'sea' part of it. OTH, you might rather do the Lake, just for a different experience.
For a real gas, go for the MES in the Beech18.... How's that for diversity? with enough coin, you can do an SES in a cub, burn some cash in the Lake, and then do an MES in a twin beech.... Just don't plan on landing a job flying an amphib twotter the next day in Greece
Keep your expectations real and you will have a good time!
Take care, Rob