We have 1 week in Iceland (last week of April), and would like to experience as much as we can. I was wondering if it would be better to book through a travel agency, or to book thing ala carte. Would I be able to experience everything while staying at one hotel in Reykjavik, or would I need to look at other cities? Also, is it better to book tours before I leave, or once I get there? Any suggestions for tour companies or hotels? With only 1 week, what activities must we absolutely do?