Definitely move (rollover) the two American Funds accounts to anyplace else - Vanguard is the best default if you have no preference. Combine them if they both belong to the same person (but I think they don't as one says "SO" so does that stand for significant other? In that case, you can't combine them and they will still belong to their respective individuals - IRA stands for INDIVIDUAL retirement account), and get out of whatever AM had you in, and into some Vanguard funds to match up with your chosen asset allocation.
If it makes sense for your tax situation, then contribute the max to the newly created rollover IRA (which counts as a traditional IRA), or create a brand new Roth IRA and contribute to that instead.
As you are saying "we" a bunch, I'm going to assume you have a spouse of some sort; in that case they should also open/create either a traditional or Roth IRA (if one of those AM IRAs doesn't already belong to them), and max that out as well.
This would take up $11,000 of the $15K you want to invest.
If you do end up maxing both
traditional IRAs, keep in mind that you might be eligible for a tax break/credit (I forget what it's called) come tax time depending on your AGI. Can double check this over on the TurboTax TaxCaster (the retirement tab in the Deductions, Credits & Payments section):
https://turbotax.intuit.com/tax-tools/calculators/taxcaster/I'd personally save the remaining $4k until January 2, 2016 and then get a jump on maxing out one of the IRAs again for that calendar year, but I could see the argument to throw it into a taxable account now too.