You weren't real clear in your OP, but if you are completely gone from the home Friday through Sunday night, you might just want to forgo any pets.
If not, go to a local shelter and get adult two cats. Look for an pair that may already be bonded, or at least two who seem to get along well. If the cats will be indoor only then get two that are used to that lifestyle. Nothing is worse that an outdoor cat being locked inside.
Two cats can play together when you are not home and that will take some pressure off of you. Well mannered adult cats shouldn't destroy your home or crap outside of their box as long as it's kept clean. Give them a cat condo or scratching post and lots of toys. Make sure they have something to climb on so they have space to get away when they want to.
Cats come with varied attitudes as far as independence, playfulness and human dependence. Spend some time with the cats before adoption and talk to the shelter workers to get cats that will be a good match for you. You want friendly cats who will provide companionship, but who aren't so needy that they can't handle you being gone for a bit.
If you decide on rats, as one person said, they need to be purchased at least in pairs so they can keep each other happy, plus they will need to be let out of their cage for exercise daily. Three days in the cage is a long time for rats unless they have a huge cage. Rats are extremely social animals and act almost like small dogs if handled when young. Making them spend most of their lives in a cage is cruel.
Consider any pet you get a companion you will have for their entire life, and that relationship will take work on your part. Pets are not on-demand companionship that can be turned off when you have other things to do. Sounds like you are going in to this with a good attitude, so kudos to you. Good luck.