The same applies to reels, but generally a reasonably priced "025" or "030" size spinning reel will do for most applications to start with.
For the very young, the "Coffee grinders" with the push button on the back are the easiest to use, although they do have their occasional birdies etc.(Just to keep Dad busy.)
There are many arguments as to which reel to use, as they all have their different uses, and some like a fast retrieve, and others don't mind and so on, but to start with the standard spinning reel is quite adequate and generally reliable and easy to use.

Many of the "Pros" will use one favourite rod for several species, and just change the line size for the different applications. (Others of course, have a seperate rod for each, which may or may not actually make a difference.)
This is a good lesson for the younger anglers as they will learn that big fish can be caught on little rods and light line, and generally the enjoyment is greater with the extra effort of playing the fish with light tackle.

The reel should be "matched" to the rod to enable balance of the two. A huge reel on a little rod is cumbersome  and makes one rather tired just holding it (never mind it looks stupid), and the point of balance should be around the reel seat, normally just in front of the "foot"of the reel.
The reasons for this are that holding the rod, becomes tiring on ones wrist if the rod is always leaning forward or backward around the point of the reel handle, or where you are holding it, since one has to try and hold the rod straight to watch or feel the bites.
After a while it all just becomes too heavy and you tend to put the rod down, and guess what, that's when you get the bites and miss them.

To check the balance of the rod, simply put it all together and try to balance it across ones finger somewhere in front of the reel. The closer to the "foot" the better.

For ease of  casting (although it doesn't help Dad with the Birdies), the line should be kept fairly full on the reel spool, but not so full that it just keeps peeling off when one opens the bail arm.