It's doable but would be draining in the long term, especially if done 5 days a week, would it be possible to mix and match with public transport or driving part way?
We've had similar discussions before and, for a lot of us, it came down to time as much as distance, though 30 miles each way would be at the extreme end distance wise. IIRC most people favoured something in the 30-60 minute range, depending on the person that probably covers an 8-20 mile distance.
Having done a 40 mile round trip daily, though not for that long, I came to the conclusion that about 13-15 miles each way would be my ideal. You can always extend on a Summers evening etc if you fancy it. Oh, and terrain will matter as well, mine was fairly flat, or pancake by some peoples standards
