Hezz, I'd mention to him, since you said long hours, that there are some things that just don't do well in a crock pot for a long time, even if you have one that switches to warm after a certain period of time. Chicken breast and pork loin will generally end up pretty dried out if they are cooked all day. Meat wise, you'll have better luck with things with a higher amount of fat like chicken/turkey thighs or legs, pork butt (shoulder), fattier cuts of beef. I do whole chickens in mine with good results - leave the skin on to help keep it moist during cooking and then remove afterward. Soups and stews generally do well for long periods of time as long as they don't have pasta or rice - but rice or smaller pasta can be thrown in for about half and hour when you get home and they will get soft. Recipes with dairy will sometimes curdle if you leave them for long periods of time as well - cheese and 'cream of' soups usually hold pretty well, but if you are adding regular milk, cream, or sour cream it is better to do it at the end.
If they want to do something that requires watching a little bit more to keep stuff from drying out or going wonky, they could do it on the weekend and then pack up meals for the week. I will sometimes do a bigger piece of meat on Monday (shredded beef, pulled pork, whole chicken, turkey breast) and then use the leftovers to make meals for the rest of the week - sandwiches, quesadillas, pulled pork pizza, soups, etc.
I made a LOT of slow cooker meals when I worked late so that DH and DSD would have dinner ready when he picked her up.