Several great resources have been listed here, but I'll add to it. Although primarily designed for manned aircraft pilots, a fantastic app is
Foreflight. It's only for Apple, but gives you everything you want and more. From VFR sectionals, to weather, to the Airport Facility Directory giving you very detailed information for each airport. One of the issues mentioned here with Class E airspace is when a control tower shuts down, sometimes the airport does become Class E. The Airport Facility Directory tells you for certain, or whether it becomes Class G, and will even give phone numbers should you need them. All updated when the FAA updates their information. It can also help determine whether you are actually in controlled airspace (Class D airport, as an example). Many of the apps designed for the UAV community are really crappy and don't draw out the airspace correctly. This will do that for you and more as it will overlay your position right on top of the VFR sectional, so you always know.
It is so accurate and complete, the FAA has authorized it for use as an electronic flight bag equivalent for ALL types of flights, even Part 121 commercial (scheduled airlines like Delta and American). Many of the features are for manned aircraft, but at $99 per year, if you do even part-time UAV work, it is well worth the money. They aren't marketing this to the UAV community, but it is so cost effective, I'd recommend it.
Disclaimer: I am not in any way, shape, or form associated with Foreflight. I just use it for both manned and UAV flights.