Yes, you can access Park Ventures at ground level from Sukhumvit and use the same escalator. I prefer going this way because it avoids the noisy main road.
In respect of the PA, I’ve always enjoyed staying there: good upgrade experience over many, many stays, lovely breakfast, great pool. The lounge is *ok* and is great for a group, but the food is pretty mediocre IMO ( and nothing like the variety/quality of the ROS), ie edible but not memorable. But they offer nice drinks in a very pleasant environment.
I stopped staying so much because it got too expensive. 5 or 6 years ago it was common to see rates in the threes, now it’s rare to see it much under 6500 ( so including tax that gets close to $250USD). At that rate it’s not great value, especially when perfectly good alternatives are close to, even under, half the price.