Be aware you can book for hotels via United, Avianca and other airlines via their own portals or via Rocketmiles or United Hotels portal. From time to time they have great offers or promotions that are worth taking. Not long ago I took one 10k for first hotel booking on Rocketmiles which was 120USD a night (usually about 95USD in other OTA) but 25USD more for 10k miles? Amazing deal, sometimes they run multipliers and stuff.
You can even credit nights of for example some hotel chains like Marriot hotels into airlines programs if you wanna pool them into one place even tho at bad earning rates sometimes but better than having a few useless points here and there unless you usually stay at these properties.
The same way happens for car rentals, trains, cruises, events and so on. Some even have partners in a few countries where you can earn miles by dining or shopping (including online) with great returns.
Something I found having a good deal and useful for some people is for example buying goods from United with miles, like Tumi bags offers an usual high value for tangible goods of almost 1INR per mile.
Same goes for other luxury sorta stuff. Overpriced brands but they are usually good quality at least but if you're into that you're getting good value subjectively speaking. This is great for those who like stuff rather flying or hotels, or those who have a large bank of miles and would rather have such things.