I use Hootsuite, and I love it! I have the free profile, which allows you to connect up to three social media profiles. I also use Instagram, Facebook, and Twitter for work, and it works great!
A few small notes – you can only post four photos at a time on Twitter, and one at a time on Instagram. I don’t remember off the top of my head if there is a limit for Facebook.
A quick work around for the Instagram thing – just schedule Instagram posts through the Publishing Tools on your Facebook profile. You can schedule multiple pictures from there.
Best of luck!