Many hotel loyalty programs these days offer the option to convert their loyalty points to airline miles, but you may need to sacrifice some value in this process. For instance, both Hilton and Club Carlson offer an interesting exchange rate of 10:1 with most of the airlines, whereas IHG offers a bad deal of 5:1. In general, it is not a wise idea to swap hotel points for miles, unless you are sure that you will not use up the points for hotel stays.
If you need to swap hotel points for miles, it will be better to transfer large quantities of points, as you can have a better return with that. For example, suppose that you are planning to exchange Marriot rewards points for airline miles. If you transfer the points to American Airlines, you can have an exchange rate of 5:1 at the lowest tier, which improves when you go up the tier. At the highest tier, you can have values less than 3:1. This is why it is best to transfer large quantities of points.
If you are transferring to MileagePlus, you can have even better returns, as Marriot has partnership with United Airlines. Here, you can get returns of nearly 2:1 at the highest tier, and it would be a fair trade. If you were able to take advantage of any transfer promotions, you might even claim better returns on transfer.
United Airlines is also one of the most rewarding programs when you book Marriot hotel and air packages bundled, as you can have a 10% return as mileage bonus with that. This means that in this package, you can redeem 200,000 points for 55,000 miles together with a seven-night stay in category 1-5 hotel.
You may also consider transferring your points to Southwest, as these points can make you qualify for the companion pass. Do not expect the same rate that you got with United, but still, it is a good redemption option.