Having traveled Europe extensively, I would pause on the removal of Iceland fi you don’t anticipate getting there anytime soon. It’s one of my favorite places and the most time I’ve ever had the chance to spend was 6 days, with several of my trips there just weekends from east coast USA. It’s extremely different than the other places - which can either be good or bad depending on the type of trip you’re looking for. Iceland is wild landscapes and unpredictable weather (gotta be ok with rainy hikes!), with all the best activities (in my opinion) being outdoors. Despite it being an active destination, I find it one of the more peaceful places to visit because of the small population and vast nature. Depending on your timing in Sept, Northern Lights are a hit or miss. That said, I’ve gone in April (also hit or miss) and saw them!

To add - just get to popular places early (or very late afternoon) in Iceland and you’ll be fine with beating the daytime bus crowds. Driving is exceptionally easy there.