in my experience these 3 TLDs are now common place. .com, .net, .org.
increasing in popularity are: .tv, .info and .biz.
you may find some helpful info here:
http://en.wikipedia.org/wiki/Domain_name and here http://en.wikipedia.org/wiki/Top-level_domain
and Pam I not sure how only some of you pages cannot be seen. I suspect you have more than one domain name for your site? (i.e. www.website.com AND www.website.net) I would check with your hosting provider as there is probably some configuration problem on there end which should be easily solved.
And back to Chinnu`s question. I would stick to the norm for now. .com. or .net (hope that what you want is still available) At the base of it all you customer will remember these a lot easier.