My aunt has been numerous times (my uncle just a couple). She loves it there and knows a number of people there. We are doing it on our own (driving). Mostly staying just outside of Reykjavik. Doing a horse tour, kayaking at a glacial lagoon to the east. Lots of waterfall stuff. Geysers.
A lot of time unplanned so we can drive around and do things spur of the moment.