I'll be on Samui and Phangan for 2 weeks, then Bangkok. Will I be very annoyed with a rolling suitcase on the islands? Been a while since I took out the ol' pack...
Mostly that depends on how you're used to travelling. Overall I'd say that you'd do better with a backpack or over-the-shoulder duffle (this is what I use) than with a suitcase, unless you plan to get around by taxi. Sometimes when you arrive at a resort someone will take your bag for you to your room, sometimes not, so it's best to be prepared to do it yourself. Seldom on the islands will there be smoothly paved pathways between the street and the rooms.
Why not the best of both worlds - they have pseudo-backpacks with wheels on them. I've got a great one by Eagle Creek, but I've seen lots of makes now. I would estimate my "wheel" time at 80%, and the other 20% spent lugging it by the handle or as a backpack.
I went from Oregon to Hong Kong to Bangkok to Krabi to Rai Leh Beach, and the only time I saddled up was the 100 yard stretch between the longtail and the hotel.
