If you go Red Sea, consider the new c-250. It has an upgraded skimmer. The older model is great but the skimmer requires a constant water level so an ATO is usually mandatory & though it works fine it's a little tricky to dial in at first.
The system works great but you trade off simplicity & sleek looks for a loss of flexibility. It's an easy system to live with & work with & you can maintain any kind of reef you want. You will probably find you will want to supplement the standard pumps with a variable speed unit like a Vortech.
No sump means reactors need to hang off the back and you won't have a macro algae refugium. But I never missed it. And it's a T5 system which I prefer over LED but it's fine for SPS & can be upgraded if you choose. Lifereef makes an in cabinet sump skimmer set up if you want to go that way but it's expensive.
Of course if your aunt & uncle like the "big fish" any 65g has limitations. If they or you are tinkerers who love fooling with hardware as much or more than keeping the animals, a custom set up is the way to go.
If you are buying all new you are likely to spend less with the RSM. The RSM canopy is excellent & makes daily tasks & tank access for maintenance very convenient & easy. I've never seen another canopy that can match it and a canopy was mandatory for me.
I am still satisfied with the RSM 250 after 4+ years. It was really the only option for me when I started in the hobby. I would have made numerous mistakes piecing together individual components, LFSs had limited choices on reef ready tanks & other equipment & the staffs lacks wisdom, practical knowledge & the ability to educate plus their pricing is stupid high. Also, many of the custom tanks I saw in person and on line all looked aesthetically unpleasing to me & not suitable for the living room. I just couldn't find the system I liked, but to me a nice reef in a RSM looked like a fusion of art and nature.
The RSM kit went together in a few hours and I avoided all the newbie mistakes like leaks, sump design, sizing pumps etc. With that said I will upgrade to a custom system one day now that I have the skills & knowledge. Good luck with your project.