Iceland trip! (Reykjavík)

Hey :-)

Together with my friends I'm going to visit Iceland in March Protected content . I've created a first plan of the trip and I google multiple website to find the best places to visit. However .... I want more! Which part of Iceland would you recommend. Maybe some tips regarding events or places worth visiting in March? Car rental, accomodation. I am open to all tips guys:)) Cheers!
Kasia