If you choose only one showerhead, opt for a handheld unit. Buy one that attaches to a vertical pole and slides up and down to serve users of all heights. If you include multiple showerheads, be sure the capacity of your water heater is large enough for the increased demand for hot water. If you still want a tub, don't plan an additional step up to get into the tub - you'll end up with a bigger step down. And avoid sunken tubs.
Whirlpool tubs are another area where bath plans often founder.
If you install one, note where the motor is located and plan an access panel or order a tub with a removable skirt. A simpler solution is to create an access panel within a bedroom closet if the tub shares a common wall with one. You'll also find these large, wide tubs easier to clean if you install a handheld shower on the deck along with the tub filler. Remember, before buying any tub, carefully measure the doors and halls on the way to the bathroom to be sure the unit fits through them. If space permits, locate the toilet out of sight, for example, behind a partial wall or in a separate water closet.