I always keep the crate door open all day long if I'm home. Chloe is 5 months old and I crate her when I go to work. I put her favorite toy in with her.
I used to feed her in there when I first brought her home because I have Bailey (who is 20 months old) to keep him from eating out of her dish too and so she would be more comfortable in the new environment. I don't crate Bailey at all now, not for a long, long time.

Very soon Chloe (and Bailey did this too when he used a crate) began going to her crate and lying down on her own to nap or just lay down and rest with the door open. For quite a while now when she sees me get my shoes on to go to work she automatically goes to her crate and takes her own toy with her, lays down and I calmly close the door and nonchalantly say "bye, bye, gotta go to work"
and leave. At night I tell her "It's night, night, time" and she goes to her crate and lays down. She does this because it is a ritual and because Bailey used to go and get her and herd her to her crate and I don't think she likes this so she just goes on her own now so she doesn't have to put up with being "goosed" down the hallway. LOL I say the same words to her when I go to work and at night. Mostly dogs just sleep when we are gone anyway.