I went with an Erin Condren vertical layout coiled planner, which is very colorful and pretty, so I don't think that is what you are looking for ;-). However,

I went with an Erin Condren vertical layout coiled planner, which is very colorful and pretty, so I don't think that is what you are looking for ;-). However, the same brand has a line of neutral & undecorated planners with blue/black/grey covers. This one seems like it would raise no eyebrows at work: https://www.erincondren.com/camel-customizable-vegan-leather-focused-planner https://www.erincondren.com/camel-customizable-vegan-leather... . However, they offer fewer layout options in this line than they do in their more popular offerings. Levenger, as I mentioned, also has some good options, although they are pricey. ARC (I think that's Staples' store brand?) has a line a lot of people buy. Both of these are discbound, which is a choice you either really like or don't. Filofax & its ilk also have a lot of options that would look fine in a professional setting.