Don't change a bunch of things thinking you'll make the bike 'better', it's too late for that now anyway, you should do that before the longer ride so you can test things.
Keep the tyres / suspension / bars you know.
Time in the saddle is more important, but you need to do that for a good month I'd say. If you have been riding 16 miles twice a week, with some shorter rides as well, you should be ok. If you only ride once every other weekend, you'll probably get a sore arse.
Most import thing is proper padded lycra cycling shorts / undershorts. Next is a big bowl of porridge the morning of the ride. Next is plenty of water in a camelback for the ride, and energy food.
30 miles isn't too hard, just take it steady.