I can highly recommend the Mermaid Resort on Samui. It is on the north side, close to Big Buddha and 10 minutes max from the airport. My wife and I stayed there for two nights in March this year, on the recommendation of Ott, a long-standing forumite (thanks, Ott!). Ott was, as usual, right. The Mermaid is well-serviced and maintained, with nice, clean rooms. Great food. It is right on the beach and also has a pool. For a night or two I don't think you could beat it, but for a longer term my preference is for the more laid back backpacker-style bungalow accommodation. (I guess that's why we go to Koh Pha Ngan. ;) The Mermaid is more up your up-market resort - see the link below.)
If you book in advance, they will provide free aircon transport from the airport, if you are flying in.
The resort is about 20 minutes from where the Lompraya high speed catamaran leaves at 8.00 and 12.00 for to 30 minute trip to Koh Pha Ngan, en route to Koh Tao and Chumpon. I think the Mermaid will also provide free aircon transport to the ferry.
As to the Seaflower, I haven't stayed there but there are literally hundreds of places to stay on the island. (Check out the links below.) You could always book one or two nights and have a look around. If you find somewhere you like more, then I suggest you could bargain for a good rate if you intend to stay for more than a few nights.
Here are some useful links:
Samui Mermaid Resort, Koh Samui, Thailand KOH PHANGAN MAP: ISLAND MAP OF KO PANGAN, THAILAND Phan Ngan
I am happy to provide further info.