Personally I just wish we could use our bells instead of miles. I don't play this game daily like I do NL, so the miles I gain a day is very low compared to other folks. Especially when they expect you to spend them on other things that take up more (Like decor and stuff), and bells are easier to manage imo.
if you visit someone's island, you get 1,000 miles once a day. That's how i would maintain my miles for days where I'm too busy to play but it also helps that I have my husband's switch that I can quickly visit.