Phuket and Krabi are not best resorts to go to in July unfortunately. There will be quite a lot of rain then. Your best bet is Koh Samui. Chaweng is where to go to if you like a busy place. Bophut is where I go to as it is quieter but within a short songthaew ride of Chaweng. Others like Hua Hin which is 2 and a half hours by road from BKK. I have stayed there, had a great hotel but was not too fussed with the place. If you haven't done so already take a look through this thread where there is info on Hua Hin, Koh Samui and of course BKK.
Any further questions- just fire away!

Hi Fiona thanks for your quick reply!

How much rain on a daily basis would you expect in Krabi/Phuket , Koh Samui looks lovely but friend have just been and would prefer to go some where else.

Hope that makes sense thanks

Have a look at http://www.alexmalcolm.net/. Hes got some reports on weather for the past few years. Looks like you might expect rain on half the days in July though these might just be a shower.

In Krabi a restauranteur I spoke to said they closed down during the low season (inc. July). However it might not be so bad in a livlier resort such as Ao Nang. I would expect the Phuket resorts of Patong, Karon and Kata to be reasonalbly lively. I gather sea conditions at this time of year can be quite rough.

rainfall average is 12 inches in July for Phuket as it is the monsoon season as opposed to 5 in KS. I am sure you would get some great days even so but I think it is a bit of a gamble.
I would certainly have been to Krabi before now if the weather was better then.

Ko Samet is one of the dryest islands and only 3/4 hours from Bangkok. Train or bus to Ban Phe (sp) and boat for half hour.

Chris
Have you been there? Would love to hear some info on it.

Went about 5 years ago. Not a resort type of island mostly small family run places. Lots of info on Lonely Planet especially in the "stickies" at the top of the page. Thai familes head there from Bangkok for a break at weekends so that's when it can get rather busy. Nice white beaches and great for up to a week, after that it may be tooooo quiet.

I go to Bophut in KS because I am not keen on Chaweng which is def a resort. Koh Samet may be worth researching a bit more. Thanks Chris