Standard corner rooms at the YC are not really any bigger. The bigger ones are considered junior or deluxe suites. I'm pretty sure that there are only 2 of this style at the YC, so if you are interested in one, I'd check on availability as soon as possible. As an alternative, the BC has the same junior/deluxe suite setup and I think they have 4 of these rooms. Another consideration is that I'm almost positive that they come with concierge service. You could look at the price difference and factor in that you could probably eat all your breakfasts in the lounge, get snacks, soda and in the evening a glass of wine or beer with some appetizers or late night desserts. If concierge service is offered, that's another reason why I wouldn't wait until check-in to try and upgrade. Their pre-planning department is excellent and they'll assist you with all your advance plans.
Tammi