what extensions would you use for new site(s)

for someone who has Dreamweaver & FP ( don't worry, not using on new sites anymore)

what extension would you use.?

I like the way www. site dot com/page1/ looks

when in fact it is site dot com/page1.html

it is ot a directory just a page within a site.

I'm not liking the .html extension look anymore.

how does someone do that ?
is that making the server work harder ?
is that OK for SEO or bad..?

Thanks

 

Its good for SEO. I do this for most of my sites, using .htaccess and forcetype.

<files file>
ForceType application/x-httpd-php
</files> 

Code (.htacces):

file (no extension) will now be treated as a directory, and you can call it up as http://www.site.com/file/subcat/

Or whatever format you choose. I would recommend making it interact with a database (the "file" file). Just code PHP straight into the file