My wife and I have done Hop On Hop Off and cruises tours in many locations in well over a dozen countries. We have usually really enjoyed these as a great way to see many things and in a different way from riding in a car, especially when we have only a short time on a given trip.
Sadly, poor communication, lack of proper organization within the vendor/distributor and provider chain, and discourteous services all made for a much less than pleasant experience in Miami. We followed the instructions on our receipt/voucher very carefully and turned up as instructed at the cruise tour first, not at the hop on hop off. There we were told we had to take the hop off/hop off and also risk missing the cruise. This was contrary to the voucher instructions which was very explicit. After having to insist, quite forcefully and against our mild nature, for fear of losing our entire booking on our last day of the trip, we were finally accommodated on the cruise, but with a very sullen attitude on the part of the agent at the ticketing counter (Bayside).
Similar difficult experience at the hop on hop off, but we finally got on, and then had to stop at the office during the next stop to clear our voucher "problem" (which was unclear to us). But we did end up getting back on the bus.
By the way, another couple also had problems, and were also understandably very upset. We were unclear whether there were similar issues as with us, whether there was overbooking, or why this was all at all a problem.
We understand that bundling travel components can be problematic, but we never have had a problem before in son many other places (Costa Rica, Ireland, etc). And we never had the level of discourteous service we experienced.
We nonetheless left good tips for the boat and bus guides because they were good and not part of the problem. I wish we could divorce the admin issues above from the total experience, because we did enjoy the cruise and hopon hopoff rides themselves, but it is hard to excuse incompetence, poor training, and lack of courtesy in the travel business.
We are guessing our experience in Miami was specific and unique to this location/providers. This will not deter us from cruises and hop on hop off rides elsewhere in future.