Nice Bike and Wlecome, I am not one to recomed mods as it should be your bike and your personality and there are many options. \\; However the adjustable back rest is one I don't think anyone would question.
Seats are very subjective. \\; Every butt is different. \\; Mine prefers a Corbin seat, and so does my eyes. \\; I second the Heritage handle bars since no new line or cables are needed and they feel great.
I'm on my 2nd Road King with a 2005 FHLRI. \\; I've had Mustang seats on both mine and they make a HUGE difference. \\; I haven't sat on the Sundowner that some folks recommend, but I can tell you the Mustang makes it much more comfortable. \\; Happy touring!
Graduated up to a RK this year after riding an 883 Custom for three years. \\; Great ride! \\; I rented a RK Classic and was not impressed with the stock seat, nor was my wife. \\; The stock seat on the RK Standard is great however. \\;
 \\;
Congrats on the new ride!
 \\;
 \\;