I've owned a few million. Ok, actually about two dozen and currently have five. Most of my boating ranges from state park "ponds" with electric only up to a large lake for which I currently have an 18' I/O bowrider and a 24' pontoon.
Please, don't listen to the "hole in the water that you throw money into." The people who say that are not GRM types. They're the type of people who take their Cadillac to the dealer to get washed because they use factory-approved soap.
For the ultimate cheap ride that is super simple to transport and use, I strongly recommend a plain old aluminum tiller (where you sit in the back and run the motor directly). If you decide to add a gas outboard to the fleet, they are remarkably bulletproof, and operating it directly means there are no cables to fail. Pull a cord to start, shift a mechanical lever to put it in gear, twist a mechanical handle for throttle. If you're only ever doing calm water, look also at "john boats." They are the dime-a-dozen flat bottom aluminum boats you probably see on the river all the time. The flat bottom pays big dividends. First, the flat bottom means they draft less depth for a given weight. Second, they are much more stable for when your wife is standing up looking through a lens trying to get that perfect exposure on a Heron. Third, flat bottom boats also tend to have a bit higher speeds for a given HP. The downside is that they SUCK in rough water. They slap on top of waves instead of cut through.
John boat:
Fiberglass is primarily a performance choice. Aluminum and wood are very difficult materials to make into compound curves on two different planes. Performance hulls need that freedom of compound curves that fiberglass provides. There are other benefits and drawbacks to each, none of which really apply to "slow cruising with electric motor," other than the weight penalty of fiberglass.
I will say, the added weight of fiberglass will cause a need for more electric motor. Don't skimp on battery storage or thrust. It's not just being able to putt across the lake, it's getting back to the ramp when a breeze kicks up. Dad's boat (15' fiberglass) has a 24 lb thrust electric on it we use for maneuvering while shallow fishing. It takes very little breeze to render that motor completely useless. Electric motor means the boat should be as light as possible. Otherwise you'll be doing that thing where you are buying a larger motor and more batteries. Also, if you lose power for some reason, the boat above is super simple to row.
So I agree with TJL, except that I recommend aluminum. The Whalers and skiffs pictured above are fantastic boats, but you also see that they have 50 hp motors on them. An electric motor will be more like 1/8th HP. I agree with his assesment that boats like the one I pictured below are not the best for slow-touring beginners. They are for people who need to go somewhere in a little chop, but they are very unstable. It's not overly likely they will capsize, but one little re-adjustment from you while your wife is standing up will put her and her expensive camera in the water pretty easily.
The other reason I am leaning toward aluminum for you is simplicity of care. My aluminum v-hull sits in the field year round. When I want to use it, I flip it on it's side, hose out the leaves, and throw it in the truck. Also, many fiberglass boats are made by sandwiching plywood between layers of glass. There are plenty that use a foam core, and even some that use layers and layers of solid fiberglass. If you're not careful and purchase one with a plywood core, it's only a matter of time before the glass gets a hairline crack from flexing, setting down an anchor, or UV and the plywood becomes dirt. My one aluminum boat is a 1958 model and despite hard use for 3-4 months a year, the only thing I've ever done to it was replace the wood in the transom where the motor hangs. The gelcoat on fiberglass also is not terribly UV resistant and gets chalky.
If I were you, I'd be looking for a 14' aluminum flat bottom john boat. Wider is better. Put a 24 lb thrust electric, one big H8-style deep cycle battery, and oars with oar locks. You'll use it this summer, then this fall when everyone is selling their motors, you'll find a great deal on a 6hp, 7.5hp, or 9.9hp Evinrude or Johnson and buy it. I usually have some around, but right now all I have are two wasted 30hp versions.
Had a real nice wide trailer too. I like the wide trailer so i pretty much have a step anywhere around the boat when its on the trailer. Plus the wider axle has it so i can look in either of my side view mirrors and see my tires. See that the tires are looking good and if im in a tight spot, easy to not hit stuff. 
