I have never been before, so this is the best I can offer;
If you like all the atmosphere for the hustle and bustle building up to the intense start of a race, then the main grandstand on the start-finish straight will be best.
However, for overtaking, I'd suggest Turns 3 and 4. With Turn 3, circuit designer Hermann Tilke wanted a place where overtaking was
likely rather than just possible, and thus created one of F1's longest straights into one of its tightest corners. The straight is entered via a slow corner, so the chance of gaining a slip-stream and tow to gather speed is even better. Furthermore, it will most certainly be a DRS zone.
If a driver gets Turn 3 wrong, it wrecks his speed down the straight into the tight Turn 4, so it's a make or break corner.
I hope you enjoy the race. Last year's was a cracker.