Depending on your budget it may be cost effective (and otherwise more advantageous) to consider trains and/or other air carriers in some cases, as opposed to using miles - even if realistic award routing options were available (which as noted above isn't so much the case in your case)....
Rome-Venice:
The high speed
Frecciargento train from Rome to Venice takes less than 4 hours and should start out at something like $50 (USD) per person if you book in advance. They only open up schedules around 3 months out so keep an eye on it for when August dates will be opening up. The train departs right from the Termini station in Rome which is likely more convenient to your lodging than either airport.
Considering the airport hassles and advance arrival times for security, luggage, etc. your door-to-door travel time on the high speed train won't be appreciably different from schlepping to the airport for a flight and the risks of delays and cancellations are much, much less.
http://www.trenitalia.com/
Click on the language selection in the upper right for English. The city names in the dropdown boxes will still be in Italian but it's pretty easy to figure out - Roma = Rome (you'll most likely want to use "Roma Termini" station) and you'll want "Venezia S. Lucia" for Venice.
If you're looking to be super thrifty and have the time, a slow Intercity train can be in the USD$10 neighborhood but takes longer. I'd recommend the high speed train though.
Venice-Munich:
Check out this for information on rail options for the route (btw this site in general is a good resource for European rail travel info):
http://www.seat61.com/international-...Venice-Germany
Air Dolimiti flights run from VCE to MUC in about an hour and look to be in the USD$100 range per person, maybe lower far enough in advance.