From what you said, I'm not sure an open headphone is the best choice for you. The Sennheisers are lightweight and comfortable, but they are large. Their open design also let's noise in and out.
On the other hand, if that's OK with you, I second the recommendation for the HD598. It's a terrific headphone that's easy to drive without an amp and has a big, spacious sound. It's a bargain at under $200. With the money you save, you can buy a pair of Etymotic Research IEM's for when you leave the house.