Some manufactures offer prewireing options, ie power to the nav desk for VHF. probably a good use of $$ spent at the factory if you will, then your boat does not need to be torn up in the end to run wires! If you want an outside shower in the cockpit, probably better to do at the factory! Heat from what I can tell, is a so-so option. Some cases better to do at the factory, others save your money!
Bimini's can be so-so too. Some factory ones are great, others, you want something a bit different, so have it down locally!
Price out the options you want aftermarket, vs factory vs DYI and decide on your time availible, $$ in sheelbarrow etc. Not that this is a boat, but when I bought by Bobcat skid steer for work, I figured out which options I wanted, which were literally factory best installed, and which the dealer did. Ordered the best at factory options, and left the others be!
She drives me boat,
I drives me dinghy!