Sorry- this is long!
Its always so variable everyone's opinions. Even if you and I spent the same week, at the same resort- we both might have vastly different opinions. DH and I are experience skiiers. We like a challenging black run, but 95% of the time, are happy to just cruise about, find a refuge for an extended lunch and just enjoy the experience. We end up coming back to Italy, despite having skiied many other countries.
From the resorts on your short list that I can comment on:
Pila- Very small. We skiied every lift and almost every run on the first day! This about 18yrs ago, when it was newly opened to British package deals. We found those working in the shops/ticket office spoke Italian, some French and very little English- again, this was years ago. We caught the cable car to the main town for something different to do. This wasn't overly exciting though! Our tour company did an optional day trip to La Thuile, which we did. Competent skiiers can ski across the border to La Rosiere. I recall lots of open runs at the top and very few trees, except for getting back to the village. Your 'boys' might find Pila too boring for a whole week. The food felt very traditional and it was charming, with pretty, tree lined runs, but even you might find it a bit repetitious after a few days.
Montgenevre- only spent a few hours there (see Sestriere)
Cervinia- Large, wide runs. You can ski from there across to Zermatt- BUT, if there is bad weather and lifts close, you can be stuck in Switzerland with a long/expensive 3.5hr taxi journey! I don't know why, but we just didn't enjoy Cervinia as much as other resorts.
Sestriere- Went back twice, mainly because the hotel was so good! We stayed at Hotel Du Col which was true ski in-ski out. In the hotel basement, you walk out the back door and are on the ski run! They had a wonderful evening buffet with ample choice and endless wine too. It was right in town, so an easy walk to shops/bars if wanted.
The resort did have a good mix of runs. From there, you can get a cable car across to Sauze D'oulx and ski there all day as an option. Lots of open runs and tree lined areas lower down.
DH I planned a whole day getting to Montgeneve- via skiing. From Sestriere to Sauze D'oulx, then to Cesana, then Claviere then Montgeneve and finally back again. It was a fun challenge, but we only had a few runs in each resort. The tour company did a bus trip to Montgeneve for the day- which would have been another option to spend more time there. Others have commented on how much they liked Montgeneve, so its somewhere I have considered staying.
High winds can also stop the cable car from Sauze D'oulx, but, the taxi from there isn't anywhere as far or indirect as trying to get from Zermatt to Cervinia, plus there is also a bus service between the resorts.
Another option, but it does have a long transfer time, is Livigno. Due to its remoteness, its remained tax free. We went back several times and over the time bought camera lenses, perfume, liquors etc. This was pre-brexit, so I have no idea what the rules are now, but you might be able to stock up on birthday gifts/tech for the coming year.
Its based around 1, very long road with runs on both sides of the road. You need to check though, whether the accommodation need a bus to get to the lifts or you can ski in/out from. Its high altitude, so snow assured into April. I recall a mix of runs too. We did a day trip to St Moritz which was amazing!
I used to read the ski club website. It gives you an idea of pros/cons for each report, % of beginner/intermediate/advances runs and other tips. You don't need a log on to get the basic info. I'd be looking for a resort with a large proportion of intermediate runs which you can all enjoy.
https://www.skiclub.co.uk/