i dont decorate the cage..only the basic things like food bowl,DIY hay rack,water bowl..for toys i put them around my apartment or the corners where she like to relax..my rabbit is free roaming only cages when i'm not at home or sleeping
if u dont have time to let your rabbit out often..u can try to limit the roaming area
if u got big budget..i suggest u can get play pen and surround a big area..then put fleece cloth or wood shaving and a small rabbit cage for your rabbit to hide and some toys and tunnels will be great..
rabbit to be comfy they like a big space for them to run and binky..

you can check out sangterap "the run" and see what i mean..

The bigger the better   throw in lots of chew toy.