I was gonna give you advice on trapping them, but then I realized you were talking about their characters and not the actual players.
Then again, playing the odd session in an actual escape room might be fun.

Utility ? No idea. But Speak with animals is so fucking hilarious that I will carry a class just for it because its that funny. I was sold the second I talked to the squirrels near the bard.

I haven’t used knock at all but the first thing I do after every long rest is apply speak with animals to my PC. I then talk to almost every animal I meet.

Speak with the Dead is also pretty good too.

Knock wastes a level 2 spell slot while thieves tools are plentiful. You can easily unlock anything with thieves gloves, don't even need a dex character. Speak with animals is replaced by a potion that most merchants sell for a few gold.

Speak with animals gets a lot better with infinite duration.

And Thunderwave is the best combat spell in the game

Just because it has resources to manage doesn't mean it is a resource managing game.

D&D is a narrative game first, a strategic boardgame second. (That is why it is an Role-Playing first, Game second)

The point is to create awesome stories and memories with friends at the table. If this involves spending resources on frivolous shit, then so be it.

I'd bet you will remember stupid shit that Wizard got you in longer than when you tactically defeated a boss.

This is what BG3 fucks up in my opinion. Occasionally places will be created where you can't go to camp for a long rest, but usually you can leave and come back trivially. There's almost no need to save spell slots. You can easily long rest after every encounter and just blow all your slots as soon as possible. I enjoyed playing it how tabletop is played. You actually need to manage your slots. If you decide to just long rest somewhere dangerous you're probably going to have some kind of encounter in your sleep, and your armor won't be equipped and it takes time to put on.

Sadly, BG3 doesn't have a dungeon master to see you cheesing something and counter it. I agree the best part of D&D comes from managing resources and making do when you're running low. The fear after you've blown all your spells after a big fight and need to get to safety with low HP is when there's the most tension. It makes for good storytelling.

"The small brick you hit is gone, but it seems there are more bricks behind it."

If you shrink a door does it pop off the hinges loudly? Or are you shrinking yourself and hopping in the keyhole?

In my campaign recently I just unlocked a flying ability so I fly to the second floor and look for windows and the DM says "no there are none". I'm like bullshit. What building doesn't have windows?

I just smack the door with my sword

Axes: am I a fucking joke to you?!