However I am hoping the whole thing doesn't end up being too good to be true, or there is some huge disadvantage or roadblock that explains why the market has such high returns.I noticed that lower income multi family properties have a much higher rent to purchase price income.

Search for "auctions" on BP to read up the advantages and disadvantages of buying in auctions.

Some advantages of both:LTR Advantages- Typically more stable income- Less maintenance- Easier to self manage, or cheaper to hire a managerLTR Disadvantages- Typically less cashflow- Potential for costly evictions- Typically lower asset class/lower appreciationSTR Advantages- Typically good STR's are in a higher asset class than LTR's- People typically think the wear and tear in a STR is more, which can be true, but having staff inside with a checklist can catch small problems before they turn into larger more expenses- More flexibility if you want to sell you do not need to try to sell pre-loaded, can sell furnished whenever you want etc- Potential for owner use- Higher cash flow, typically.STR Disadvantages- Management intensive, more expensive management- Income instability- Subject to seasonalityI have both but prefer STR's. 

The lower end houses are the original homes that were built in the 1970s (4+ bedrooms, nice size lot and wooded, great schools).My question is there any major advantage or disadvantage to investing in a place like this?

Other then that I think you need to ethically act the same as you would to others in a disadvantage situation. 

I am only providing an opinion here, you are still best to check with your accountant to understand the advantages and disadvantages. 

We would also be able to market to people that are on temporary duty or to extended families that are visiting.The advantage of staying in a duplex on our land include:1) Full Kitchen2) Ample parking for moving vans, trailers, boats, etc3) Washer/dryer in unit4) Pet Friendly 5) More space and privacy than a hotelPotential Disadvantages:1) Cost to build: I expect that the cost to build the duplex will be around $85/sq ft.

I'd still have to take a mortgage which puts me at a disadvantage when buying.

What do you all think and what are the advantages and disadvantages?

Taking a good look at your average income and average expenses gives you a baseline to build on.Starting out as an agent has its advantages and disadvantages.