Have you looked at Isailor, or Inavx? I use Isailor pretty regularly, and it is really easy to use. Inavx is really deatailed but mainly uses NOAA charts and data, and can cost $$$. I have heard good things about the Garmin app as well.I like the free Skipper app for iphones and tablets.
Offshore contour maps and tide info.
Forest service maps.
instant weather info
I know it was designed for Sailors but I've been using it landlocked and like it.
I think you can download lake maps on it, need to research that.