I spent 6 years 2 up camping with my son, his ages from 11-16, on my R1150R.
The hardest part was hauling gear for 2 people without the pillion seat open.
Check out Jo's UPac. Mine is old and the seams and zippers are still like new.
The amount of stuff you can ram into these things is incredible, and when done, it becomes passenger armrests.
My kid would fall asleep in the back, and never budge.
http://www.josupac.com/faq.html
The R1100R has the ugliest OEM backrest I have ever seen, and it's $350 bucks!
You didn't mention if you had a stock seat, but if you do, the first few days of your trip will let you know BMW stock seats suck. I have a Sargent seat, with the Pirates Lair backrest. (and even added a beadrider pillion)
Luckily Sargent has a good looking seat/backreast combo for the R1100R.
http://www.sargentcycle.com/bmwbrest.htm
The upac will wrap around the backrest nicely too.
Not cheap, but a total solution that a serious road tripper would get a lot of "mileage" out of.
Take it from me, you do NOT want your passenger complaining about the pain caused by a stock BMW seat on the first day of a multi-day road trip. If your passenger has not spent 5-6 hours in the saddle on your new bike yet, do it ASAP.
Depending on butt types, the Sargent might become a necessity. It was for us.
Intercoms, I have Scala Q2 picked up on close out..... they work well.
It's a bike to bike comm now, my son is now 19 and riding.
I think they are up to Q4's now. If you have the money for wireless, skip the wires.
If not, I got a used Autocomm wired one with 2 headsets that is for sale. PM me.
Search the board for Jacket threads.
I like FirstGear for it's mid priced quality, others like other stuff.
If you have any size to yourself like I do, (not built like a skinny German) try jackets on in person before buying.
Manufacturer sizing is a crapshoot on boots, jackets, and pants.