For Want of a Heavy Transformer, I Was Almost Unable to Recharge Electronics on a Recent Trip to the Caribbean

Like many of you, I carry a laptop and a cellphone on international trips, along with a small adaptor permitting me to plug a recharging cord into the electric outlet on my hotel room's wall. But on a recent trip to the Caribbean, I nearly came a cropper on an island where the electric current generated 220 volts. Plugging into an outlet there, I found that the electricity did nothing at all to recharge either the laptop computer or the cellphone, both of which apparently require voltage of 110 volts.
 
Actually, I was lucky, according to a techie friend. He claims I ran the risk of seriously damaging both of my electronic devices. When I saw that neither device was re-charging their batteries, I hastily phoned the front desk and learned they have a transformer for such purposes. Up to my room it came, a bulky metallic object weighing at least four pounds, and looking like it would power a nuclear energy plant. On came the lights on both my laptop and cellphone, and in a couple of hours, both of them were fully re-charged. At another hotel on a different island, I simply drew puzzled stares when I asked the front desk personnel whether they had transformers. They didn't.
 
I suppose it's possible to obtain a transformer before leaving on an international trip. I've never done so before, and was disappointed to learn that the Radio Shack near where I live doesn't carry any. Previously, I had assumed that the brick-like mechanism on the power cord for my laptop computer was such a transformer. It apparently isn't.
 
Anything I'm missing here? Although some hotels apparently have dual outlets, or separate outlets for 110 volts and 220 volts, other hotels don't. How do out readers solve this problem. Do you actually lug one of those heavy transformers with you on the plane?