Idk why I always wake up with either my sides or neck or smth hurting when I wake up but that didn't happen while I stayed at a hotel. It's not like I'm an old broken man who should be waking up expecting this.
It depends on what you like. I purchased a custom made Japanese futon style mattress which is quite firm, and I really like it. It was a fraction of the cost of a typical mattress. Like, less than $1000 whereas really expensive mattresses can be almost $10k, maybe more.
I don't have back problems, but I think the futon with it's firmness helps with that. Neck problems could be caused by having too much or too little pillow.
Finding the right pillow is honestly so annoying. My dad used to have rock hard pillows that would lead to me waking up dizzy, my moms pillows were soooo soft your head was basically on the mattress. Im goldilocks but havent exactly found anything I permanently like yet.