Yeah, it might just be the stress of getting a new cage. It might be bigger and nicer, but it's just not what he's used to, so it might take him some time to get to like it. Maybe give him a special treat that he only gets when he's in the cage, to help him get excited about going in it. That's how I litter trained Flash.
As for play time, I try to let Flash out for 3-4 hours per day, though I don't always have that much time. I don't watch him every second, but my living room is pretty well bunny proofed, and I do check up on him regularly. He does just lie down to relax a lot of times, rather than being active and hyper the whole time. Sometimes he even stays in his cage, despite the door being open, especially if I let him out in the afternoon, which is sleepy time for him.
Actually, that brings up a good point. What time of day are you letting him out, and is it the same time every day? Flash tends to be active for a few hours in the morning and a few hours in the evening, and he sleeps the rest of the day. On the weekends, if I'm home during the afternoon, I don't even bother opening the cage door any more, since he won't come out during his afternoon nap.
He does tend to get bored with toys after a while. He'll play with something a lot when it's new to him, then start ignoring it once he gets bored with it. I only give him one new toy at a time, and wait for him to get bored with it before giving him the next one. For instance, I bought a set of willow baskets because they were on sale this week, but I'm not giving them to him yet. I'm waiting for him to get bored with the phone book he's been shredding every day this week before giving him a basket to chew on.