Miami: I booked through Priceline and got the Hyatt Regency for 2 nights at $38/night. I asked for and got a balcony with a partial view of the port. Hotel was really nice and we (husband Fred and I) had no problems walking back and forth from Bayside Market Place. Did some shopping and walking around. Be careful - they are really pushy in trying to get you on one of their site seeing boats. Had lunch the first day at Hooter's (yes Hooters - the girls may dress in short shorts and tank tops but they aren't sleazy and it is one of the best burger and wings around and they are only around $6 each! Not to mention that there were plenty of women customers there too.) and had dinner at another restaurant that was right on the water (sorry can't remember the name) and that was o.k.
Morning of: Since the Sheraton was only about a block away - I called and asked if Carnival was having pre-check in. The front desk said yes. We walked there and it turned out to be another cruise line and not Carnival. If you want to know make sure you ask for the Concierge. He was the only one who knew anything.
Embarkation: We got to the pier around 11:45 and there were already long lines. I think we waited around 45min to an hour to get through the lines.