@RV - Expenses for the production of income, such as investment advisory fees, are deductible subject to the 2% limit. Travel expenses related to the production of income, though, are not specifically mentioned. I think deducting travel costs to meet with an investment adviser who is managing paper securities (that is, not real property, but intangible property such as a stocks or mutual funds) would be aggressive. On audit, the IRS agent would likely question the necessity of travel versus a phone conference. Compare a rental property where you may need to physically be there, and you can see the argument the IRS is likely to make.
Given that most taxpayers won't get to deduct such costs due to the 2% limit, this isn't a frequently litigated matter; thus, I know of no case on point, so I would rely on your CPA or tax attorney to make the best decision for you based on the level of risk you are comfortable.
If you were to take a deduction for the trip, the allocation is based on the purpose of the trip and the time spent on business and personal matters. If the primary purpose of the trip was business, then you can deduct all of the airfare cost, and you should allocate meals and lodging based on whether it's a business or personal day. For more info, check out my earlier posts on airfare and meals and lodging.