I usually work in the hundreds, not thousands, but find that doing the data in excel, then copy/pasting into either corel or illy works for me.
After you paste, select text only via menu command, then inverse select to select only the boxes and lines that will come across, delete, then you are left with text only.
Tip, when dealing with more than say 50 or so, pre split your stuff into columns of 30 or so in excel, and bring them over as columns, just easier to work with.
1. Centre align your top text to the top rectangle or whatever your label shape is.
2. Do the same to the bottom one.
3. Select all your label shapes, distribute evenly across selection.
4. Select all the text in that column, and do a distribute evenly across selection.
I love illustrator but to be honest for this particular function, Corel is way faster and easier to use for me, and being able to so easily work with multipage in Corel is a huge advantage when you run out of room. Yes, you can multipage in Illy, but my personal preference for this particular type of work is corel... it's a little more user friendly (for my laser engraver in particular... Roland, not such a big diff maybe).