Just make sure the model you're getting supports S3 sleep mode (AKA real sleep mode) before hand. A lot of the newer Dells don't. Its something the OEM needs to support in the BIOS, so you can't just fix it by installing a new distro.
[1] https://www.dell.com/community/XPS/XPS-15-9570-BIOS-1-3-0-sl...
Unless it pulled a breaking Windows update at night so the laptop won't boot anymore the next morning.
I have one of those DELLs for work. Don't.