We kayak and use only double paddles. My daughter and son-in-law canoe and swear by kayak paddles in their canoe.
You'll paddle straight ahead, faster, no j-strokes (which slow you down). Two of you with double blade paddles will really haul in a canoe, and probably won't fight each other as much.
So, being a new paddler, give both a try but my money is on the kayak paddle in the canoe. The only single blade paddle I own (out of a pile of paddles) is for emergency paddling if my sailboat runs out of wind. grin
Again, rivers are best avoided until you know you can fight currents, slow and fast, and have a few practice self rescues under your belt and some river reading training. The workshops will teach that. New paddlers and rivers are done all the time, but avoidable accidents happen. An adult with a child and a swamped boat can either be terrifying or fun, all in the training. In scouts we spent more time under the canoe than in it, goofing around.
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paul, texas KD5IVP