It can be hit or miss with Emerald Aisle. If you were Emerald Executive or were trying for an SUV or minivan or something, then you might do better using aisle service, but if you're base Emerald Club then you'd probably do pretty well reserving a Premium Car. Our guess is that National at LGA is probably pretty quiet right now with almost no business travelers, so you can probably negotiate for what you want at the location if you don't find anything that meets your needs. Our recommendation would be to go for the Premium Car and save.