I was in grandstand K 2 years back, pretty much in the middle, I had an excellent view of the whole marina, so the 16-35 will be nice (take a CPL as there are always great clouds mixed with the blue sky). I also had a great view of Tabac corner (and the spectacular Maldonado crash, pic's 1 & 2 below) so your 70-300 will be nice there but take a 1.4xII if you have one. I also had a great view of the crane over the St Devote corner when he recovered Grosjeans car (Pic 3), long reach essential at this point too. I was using my 24-105 and a Sigma 150-500 that I had at the time, if I were you I’d take all 4, make the wife carry two of em’
Photos below where all taken from grandstand K.
If you’re staying in Nice then the train is the ONLY way to go, DO NOT TRY to drive in to Monaco or you’ll miss the whole event!! On Sunday (race day) get to the train station for the first train, be there 30 mins early as the queue that forms is unbelievable and it can take 2 hours to wind your way to the platform, there are food/beer outlets directly behind grandstand K which is pretty much right outside the exit from the train station, they will open the gates and allow you on to the track at the end so you can walk the whole circuit, which I thoroughly recommend. Have fun, and I’m not jealous at all