1) While waiting for the settlement offer, be wary of what you say to others--as the saying goes, anything you say can be used against you.2) When you get the settlement, see if you are giving up the right to sue the at-falt driver for any amounts not paid by the settlement (e.g. a deductible, or other costs you have borne but which were not covered, like renting a car); if you care about those amounts, either negotiate payment for them or make sure you can sue later, before you sign the settlement and cash the check.3) The parking lot would only be potentially liable IF there is reason to think that it was unreasonably careless to not have a barrier between the levels. To show that, you would need to hire and get a report from (and possibly testimony from, too) an expert, such as an architech or civil engineer who designs/builds parking gargages/decks. Only armed with a credible opinion from an accredited expert, to the effect that the design was negligent, might you have a case. Since you would have to foot the bill for the expert yourself (you can't recover it in the lawsuit; this would be your cost), it may not be worthwhile doing this: you could spend the money and lose; or if you were already paid most of your potential claim by insurance, you could spend more on this than you'd get back by suing for any amounts not paid by insurance.