Hmmm, where to start? I love Monaco and have been on 10 occasions over the years during which time, I have sat in most of the grandstands and quite a few terraces around the circuit. As we all know, it may not be one of the best races (in terms of lack of overtaking, slowest speeds in the F1 calendar etc) but it is the best to attend without question imho. I have always stayed in Monaco for the week thus avoiding the hassle of going to and from each day. The train service along the coast is good, as are the frequent bus services but they do not run all night. If you are staying in the Principality, do NOT take a car as it is impossible to park unless you prebook a space at a crazily expensive hotel. There are several benefits of staying in town, but going out in the evenings and enjoying the atmosphere or watching the activity in the garages as teams mend crunched chassis, checking out the parties on the superyachts - whose is biggest, Bernie's, Flavio's (Been a year or two since I last went!) or maybe the Force India knees up?!
Race tickets - for the Thursday practice sessions, you can buy them down there, no problem. I recommend the 'K' grandstand in the harbour leading up to the pool complex. You may not want to pay the price for these seats on the Saturday/Sunday so is a good opportunity to check out the viewpoint. If you make your way up to the back row you can also see the start/finish straight and the run down to St. Devote, also the practice starts which are fun, if somewhat deafening!
For tickets to quali and the race, the official ACM (Automobile Club de Monaco) site is best where you can choose your grandstand and your exact seat in advance. Otherwise, again it is usually possible to buy tickets when you are there and you can also search around the various bars and restaurants who have terraces and perhaps book a table in one of those. Sure, you might pay EUR200 for a pizza and salad but you also get your view of the circuit!
I could continue and bore everyone senseless on this topic! Have to sign off for now though.
RR