GPS navigation naivetee

I'm in Boston, looking for a house, relocating from Chicago.  And, since I got lost several times on my last visit, I figured we should get a GPS system with our rental car, so my wife wouldn't have to hear me muttering about the wacky roads here.

This is my first experience with a GPS - the Garmin model that Avis provides.  It looks like what I would expect from the advertising I've seen, and the interface is fairly intuitive.  I was able to enter my destination address fairly easily.  But at the outset, the unit has its hardest time.  I'm new to this system AND not completely familiar with Boston (and Logan airport), so I am missing two key things right away:

1. A general overview of the route to my destination, so I have a sense of which way to go when information from the GPS isn't clear.
2. Routes queues that acknowledge the kind of driving.
   • If I'm at the airport, give me directions that make sense with the signage at the airport (not the local road name that doesn't appear anywhere).
   • If I'm on a highway, give me directions that have to do with the exit name and number I should be taking.
   • If I'm going into a tunnel, give me advance warning of the next turn.

Unfortunately, Logan airport conspires against all of these needs for a new GPS user and someone unfamiliar with Boston.  The airport exit is all highways and signs.  There is a tunnel upon exiting the airport, and the (old) tunnel forces you to make a decision when the GPS unit doesn't know where you are and can't help you.

I have since discovered that it is possible to step through all the turns before they happen, so I could get a vague version of #1.  And you can zoom out the map and change it to a 2-D version, but the screen size and resolution aren't sufficient to give me a good enough overview map.