Trikes are generally a couple of MPH slower than two wheelers with the same engine. The comfort and savings in energy by not having to balance is the reward for a bit less speed. The tadpole (two wheels up front and a drive wheel in the rear) are the most common, but "delta" style (single wheel in front and two in the rear (one or both can be drive wheels) is also available. If it's possible to get a ride on both types you should do so. Commercial racks are available to carry multiple trikes, or combos of trike/bike. Improvising also works.
My wife rode bikes for years, but began to have balance issues so I got her a trike. Due to speed differences between my recumbent and her trike I switched to a trike, and bought her an electric assist so we could ride at my speed. Lots of options. Also trikes are generally more expensive than bikes, but there are lots of used ones available at substantial discounts to new ones.