In no fixed order ... the Golden Circle Tour, relax in the Blue Lagoon, take a tour to Jokulsarlon Glacial Lagoon (a full day but SO worth it), a trip of the Rejkjavik area ...
If you want to tailor make, I would invite you to contact Iceland On Track who hosted us a few years ago - their website is
http://always-iceland.com/ - and let them show you the interior* as well as the famous sights (* they have the expertise of 'no roading' that we can only dream about!).