I just got back from the Eagle, Duane, and SG - It was my second time diving the SG and the Eagle.
The SG is easy to penetrate, as there are large holes cut in the sides, and many of the doors have been removed... The SG also has ropes run through many of the hallways.
The Duane, is similar, where the doors have been removed, and lower decks are sealed, to prevent penetration into unsafe areas.
The Grove is SO big... You should have a plan as to what you want to see.
The Eagle is a GREAT wreck, and you can see most of it on one dive. For all of those dives, the average depths on the Duane and Eagle are around 100' with the bottom at about 120'... The SG... you can go to 132' to look at sand. You can spend the whole dive at 90' and see a lot.