I like using flippers.
I feel it gives a better work out to my legs while my arms are doing their thing.
I like the half flipper thingies, instead of the long snorkle/scuba flippers. The pool I cough go to has flippers and mitt things available for free use.
Varying your routine helps to keep the monotony down. and exercise the muscles equally. You don’t want to look like you are training for the Olympics and have overdeveloped back muscles, unless, of course, you are into that kind of non-girly look.
I like doing ten laps of freestyle, breast and back stroke, and then a side crawl. If I do each three times, I think I have about 2 miles in.
As for goggles, having just perused the goggle section at a variety of stores ( all are clearanced now) I bought a good pair of speedo’s that have anti-fog, which was very important to me. I think mine were originally $24, bought for about $6. YMMV.
But, I think I might dash out and buy the kind of goggles that are more like scuba lenses ( bigger on the face) and won’t put pressure on the eyes and brow, giving the raccoon effect after about 30 seconds. I’ll probably get a snorkle too, as every long distance lap swimmer I see uses one and, frankly, I think it’s fun to breath like Darth Vader, and I might hum while swimming to scare any child who wanders into the lap lane.