I've been back to work a year now. The best thing is realizing - knowing from my own experience - that all my anxieties and self-imposed guilt trips about going back to work were completely unfounded.
I miss dd a lot of the time that I'm at work, but I know that she knows how much I love her, and I can see for myself that she is a confident, happy, outgoing, well adjusted little spirit who is very well bonded to both me and dh (who stays home with her). The proof of the pudding, as they say. If she's happy and healthy, why would I feel guilty about doing exactly what we're doing?
I was afraid that after I went back to work, she wouldn't see me as her main source of love and affection and comfort and stability anymore (all the things that mean mother to me). But she does. If she falls down and gets a bump when I'm not around, dh is well able to comfort and console her, as I'm sure a consistent and capable child care professional would be.
But if I'm home, only my kisses and cuddles will do. Because I'm still Mommy.
Knowing that for sure is by far the best thing about being back at work. Also, I love my job and it's in a field that really allows me to contribute something good to society, and that is a great feeling.
Adult conversation, coffee breaks with colleague friends, solo bathroom trips, feeling challenged again in different ways, the excitement (from both of us) when dd and I see each other at the end of each workday, all very positive things as well.
Also, I find that being at work is better than ever, too. On good work days, I think "God, I'm so lucky. So lucky to have this job, so lucky to have dh and dd. This is the best of both worlds, for sure." And on crap work days, I think "Oh who gives a shit anyway, this is only work - real life is waiting for me at home and I'll be back there at 6pm. Three more hours of this shit til I'm back with dd and it won't matter at all."
Best of luck with your return! IME the thought of it is much, much, much, MUCH worse than the reality. :)