In the States everybody is so concerned about liability.... We tried to store at Hertz (where we dropped the rental); no storage facility, no luck. Try a hotel; I tried several, if you are not a guest then they are not allowed. I tried the Information Centre; no luck, they had some bad experiences.... in the past. But they could not realy help me any further. One advise: try the Greyhound Bus Center. And yes! there you can store your luggage. Even my somewhat bigger suitcase. The lockers are somewhat small but high and deep enough. First 3 hours is to be paid for; $ 3 and after that a dollar for an extra hour.
Dimensions (Note that, in English-speaking countries, even those commonly using metric measurements now, locker dimensions are usually clean numbers of inches or feet, while the corresponding metric measurements are uneven, involving decimal places when precision is required, presumably resulting from continued use of locker designs based on feet and inches, unchanged for decades other than for cosmetic features.):
Just so you know I have tried to call and email and left multiple messages trying to find some middle-ground and give him an opportunity to make amends as I know how determinantal negative online reviews can be for a business but they have not returned a single call or email and know that we are back in FL and she has lost/had stolen many, many expensive and sentimental things we have no choice but to share our story so that know on hopefully ends up having a similar experience.  

Locker Denver