Do you have a grill picked out?
Reason I ask is I had a Weber 6 burner grill, and my ex-wife paid some one to run the gas line to our deck. Run was about 40'. They did not use a large enough pipe, so the grill never got hot enough. (I think they used 1/2")
When I moved out, I rented a house for 2 years, and put my own gas line in, I used a 1" pipe out to the deck and the grill worked a lot better.
So use the largest diameter pipe you can, cause once it is installed and covered up, you can not change it! Bigger is better in this case.
I just looked up the specs and for my grill they say runs under 50' should be at least 5/8 OD Tube, and I believe that should include the hose that goes to the grill in that length.
#1, T off of a larger pipe then you are going to use, to ensure you have enough gas volume. (or the main line)
#2, Use a large enough pipe to where you will hook up the grill.
#3, I put a shut off where I teed off of the main line, and also at the end of the line where I had a quick coupler. (the bozo that did my first house, did neither, and under speced the line)