I do like he bowl type stadiums over rectangular. One of the best examples is the Bolton Wanderers home (what ever it's Called now)
The sweeping lines of the roof do make it pleasing on the eye.
Another aspect is ease of access from the road network, so edge of town rather than city centre.
But most inportant to me is been able to stand and watch my rugby. I may be getting on a bit now, but I don't take a tartan rug to games yet.

For RL in this country, something shaped in a similar way to the Keepmoat but with one of the side stands (west side) slightly bigger. Capacity of 20k. One end fully standing, one side (west) fully seated. The opposite side to have seats at the back and a decent sized terrace paddock at the front. The other end would be a mix of seats and standing for visiting fans.

Massive car park close by, 6 pubs within a half mile radius.

TBH I don't see what the fuss is about not being able to stand, the seat gives you a guaranteed amount of space (ok some grounds are worse than others but still), you can also get your 'spot' with a seat more often than not particularly if you're a season ticket holder.

Standing is not much cop for kids, especially so if it's packed and IMHO I still think it isn't ideal from a safety POV. Sure if they're standing at the front but then they are at such a low level it's hard for them to see everything as you're already that much further away from the action at the ends.
I loved standing BITD and when I started going on my own to the Boulevard at the age of 9 I'd stand right at the front on a bit of wall pretty much right next to the speedway gates. I went into threpenny a few times when I was older but it wasn't ideal unless you stood near the front from a viewing POV.

Apart from the car park you've just described the New Headingley

I know Hull KR's stadium might not be the best, but the East Stand has to be the most atmospheric in the English game.

Still think all seating affects the atmosphere, ideally for RL there should be some standing, must admit though when your lot boo the ref it can be deafening

An inevitable consequence of poor personal hygiene en masse.

Concrete standing and a tin roof amplify sound but really there is far more than that to make a good stadium.

What suits me is an unobstructed view that provides some cover from the elements and is built to be close to the field. Obviously grounds shared with football clubs tend to be bigger and have better facilities but there are some good smaller grounds as well and a full up stadium looks better than a half empty large one. One style doesn't suit all but keep the fundamentals and you won't go far wrong. Rather like a decent ref, you can concentrate on the game and not notice a good stadium seat (or stand).

Anyway I also think Doncaster is a good template for an RL ground, you could I suppose build up the sides to increase capacity. I also think Leigh have a decent ground suitable for the smaller clubs. If Widnes didn't have that godawful pitch then its quite good there as well. Older designs have had their time. I enjoyed them back in the 70s & 80s but really we have moved on since then.

Sometimes that's the issue.
Because you're guaranteed a space, you can't move elsewhere into the atmosphere. You can't congregate. If you're stuck in a boring area, unless there are enough seats to move there's not a thing you can do about it. That's why terraces always tend to have a better atmosphere than an all seater stand.

Location is so important, look at Salford. Parking, transport links, local amenities (pubs etc), doesn't take 3 months to get away from.

A mix of terracing and seating is good, as it gives people a choice. I prefer the way Leeds are doing it with the Southstand with terracing below and seating above.

Bowls over four separate stands.

Baby changing facilities

Whats up with a field with white barriers on one side, some farmers trailers at one end to sit on, a temp stand for 200 at the other and a bar, gym and 200 seats as a main stand.

That's what you are getting if the Broncos come up. Stacks of viewing variety to support everyone's needs.

In fairness, they put on a cracking BBQ when Leeds were there last year.