Not familiar with Sandpiper, but have stayed at Royal Palm several times. Great location for walking to many different places. All units full ocean view. The restaurant there presumably still sucks, but otherwise, it's a good place to stay. Too bad they did away with the bar above the front entrance, that had a great view of the bridge openings.

As far as cell phone, if you are where there is wifi, you can use your phone without any extra cost to you. Royal Palm would have wifi there, so if you're there, you would have no problem. Otherwise, if you need it for an emergency, it will cost you a couple bucks a minute. Or check with your carrier about an international plan. Many run $10 a day, or some flat amount per week or month.