The I-Drive OCCC area is highly walkable and pedestrian friendly. If not, there is a trolley, shuttles, buses, and cabs.
Any hotel you pick in the area should be fine, but as always, you get what you pay for. If the convention is large enough, hotel pricing will reflect it.
Spring will be lukewarm, so consider if you will be dressed up and walking in warm weather.
The hotel down the road may be $80 vs $150 in the OCCC complex, but if your promptness, comfort, and safety are factored in, the $70 difference is a small price to pay... and it won't make much of a difference in your budget.
The Westin is on the other side of the complex on Universal Blvd. I love Westins, but you'll need to cross a rather large parking lot somehow to get to the OCCC... and you will pay.
There's a red roof, a hojo, a days and a few other budget hotels on Hawaiian Court across from the OCCC on IDrive, but I can't vouch for their quality. Rosen owned brands are fairly good around this area.
Try not to have too much fun, it is easy to miss your meetings around there.