My husband is in his 50s, so yeah, Morning Wood is the hardest. Oddly, he prefers anal in the evening (usually because we usually have marathons at night, and are more likely to have anal during a marathon.) The first few times we had anal in the morning, I was a little anxious, but not anymore.
He usually has to empty his bladder before we have sex. So, I lie there yearning for him, as he tries to coax his poor swollen member to release that valve so he can go. Neither of us are comfortable having sex with a full bladder, but it doesn't seem to matter with his hard on. He's still pretty firm even after he pees.
Men have higher testosterone in the morning, so it makes sense that they'd be harder.