Well, I ordered some items online and installed them all this week, the bed extender installed on Wednesday and the tonneau and running boards this Saturday (yesterday.)
Note: I tried to purchase these items locally...at a Carmax and a Nissan Dealer. Both Parts Departments didn't seem interested in my business at all.
BED EXTENDER:
Let me start in the order of the items I installed. I purchased a Sliding Bed Extender from nissanaccessories247.com. The item arrived within the week. I paid about $250 for the bed extender kit.
This item was the hardest to install for several reasons. First, it arrived on a Wednesday and I started working on it late when I was tired. Second, I was arguing with my girlfiend, nuff said on that.
Originally, the install was going easy. Too easy. Let me list out some advice if you plan on installing this yourself. It's all fairly simple up to a point but when things go into detail, the directions fade:
a) Check the type of screwdriver required. It requires a T-20 Torx wrench/screwdriver (which I didn't have) so I had to make a mad dash to the autoparts store before the 9pm closing. This isn't mentioned till the very END of the process. Check your screw requirements first thing. And I used it for twelve screws. BTW, I did try flat and philips head screwdrivers of various sizes that did not work. T-20 Torx: $3
b) The hanger from which the bed extender pivots installs from the cab end of the rail system to the bed door. All cleats and security bolts must be removed from the railing system before you begin.
c) Pay attention to the orientation of the installed support struts. Make sure they follow the pattern of the larger pieces of the bed extender (see photo.) I installed one upside down and had to do it over again.
d) Lightly use a hammer to tap the female piece of the strut support anchors in place (see pic) to prevent them from popping out while screwing.
They kept popping out on the first go round of the installed. Tapping them in made the whole process much easier.
e) Install during the day or in a well lit area. My bed liner is black and so is the bed extender. After nightfall things got hard to see.
f) Keep all of the strut support anchors in a cup while you're working. Easier to access.
All in all, it wasn't too bad. The instructions could have been a whole lot better.
Assembly and install time (including trip to autoparts store): 1 and a half hours.
TONNEAU:
Okay, I decided to go with the Polycarbon (versus metal version) tonneau from BakFlip. It is the Bakflip 2 F1. It is most expensive model and mine cost $889. I purchased it from Autoanything.com online. Shipping for the tonneau and running boards was free.
What sold me about the polycarbon model was that it is very secure, holds 400 lbs, works with the bed extender, doesn't get hot in the sun, is lighter in weight and, in online reviews, seemed to hold up better over time. I had my old Frontier for almost 11 years, so I am about things lasting. An online letter from the owner of the company in another forum seemed sincere in the desire to make a quality product. Something that lasts.
The install was a breeze. I worked alone too. While the paper instuctions were spotty. I had taken the standard cleats and security bolt off the rail system on one side but after installing the tonneau frame, then realized that that wasn't necessary. It all works together like one big beautiful family.
The install process is simple:
a) Install the frame with the given anchors. ***Note that the given anchors are
above/resting on top of the nissan-installed rail system.***

b) Install the panels

c) Secure the panels
d) You're done.
My truck didn't require any of the shims and gaskets to be installed. And I haven't installed the drains (yet.)
Assemply and install time: 45 minutes
RUNNING BOARDS:
I purchased
Steelcraft 3" Round Step Nerf Bars, black for my truck through Autoanything.com, paying $185 and free shipping with the tonneau. I would have purchase the bed extender thru this company as well but their selection of bed extenders wasn't very good.
PROS:
a) On my 2011 Frontier, the bolts were all ready and waiting for the running board hangers.
b) Installation was very simple.
c) Instructions were complete and color coded with the parts.
d) Installation was easy.
CONS:
a) Both driver and passenger side running boards had small, outward dents in them. I considered exchanging but the dents were not big enough(in my opinion) to sweat it. They are black and the only person wouldl ever really know is me.
Assemply and install time: 40 minutes
Here are the final results.
Before:
After
I have included the prices paid at the risk of someone telling me I overpaid. I was satisfied from the research that I had done that the prices were in the ballpark.
I call my truck YETI...My old truck was BEAST.
Here is the Yeti window cling I made. He is hard to view thru the darkened glass but when the light is just right he is easily seen by the traffic behind me.
Here's a closeup...
If you have any questions, let me know.