I've encountered the same problem. Closed guard works very well, particularly if you learn to incorporate your legs to disrupt your opponent's balance, because it slows your athletic opponent down. My primary goal is to take the back instead of attempting to sweep or submit from that position as those require bigger "windows of unbalance," which is often difficult to achieve against the kinds of opponents that you refer to.

One approach to get the back is to dominate the lead arm from closed guard and direct my opponent's elbow across my centerline in order to achieve "side-guard." From there I work to take the back, applying arm locks or strangles only opportunistically until I reach the back. I use my entire body and various combinations from the closed guard to move the elbow across the centerline.

For example, from high-guard (one leg over the shoulder from closed guard) you can extend you hips, making your opponent's elbow susceptible to center line displacement. Once the elbow crosses, bring your knees towards your chest; you'll end up in side guard ready to take the back while your opponent is in a weaker position.

If your opponent is standing, you would still dominate the power hand and work from leg entanglements, such as RDLR, to achieve closed guard. Alternatively, you can work your ashi-garami game if you feel very strong sweeping from there and you have developed a strong lower body attack system.