Agreed with jwnrw...any entry-level DSLR will do just fine. If you like the feel, look, features, and price of the D3100, it would be a good choice - as would the equivalents from Canon, Sony, Pentax, & Oly. No worries.
I also agree that you may need to determine whether a DSLR is needed or wanted, truly, for what you intend to use it for. Not to say a DSLR cannot do anything you need it to, because it can. But it can do far MORE than you may need, and may in some cases be too many compromises to achieve a goal that could be done with something smaller (size, weight, portability, multiple lenses needed, sometimes additional processing needed to equal the peppy output from a P&S, etc).
Sort of like buying a 400HP, all-wheel drive, German executive luxury performance sedan when all you need is to commute to work and back, by yourself, at a maximum speed of 45MPH. Sure, it can do that job too - but so could a Honda Civic...and arguably the Civic could handle the 45MPH and stoplight to stoplight commuting equally as well as the German luxo sedan. The Luxo sedan has lots more features, lots more power, and can go extraordinarily fast in all conditions, but it doesn't really do 45MPH commuting any better than the Civic.
If you shoot mostly casually, mostly snapshots and memories, mostly daylight such as landscapes and outdoors, and rarely delve into manual control of camera settings, then you may only ever be using 1/10th of a DSLR's abilities, and could be shooting well within the capabilities of a good P&S camera like the afformentioned G series Canons, FZ series Panasonics, HX series Sonys, etc. And the conveniences of those systems may outweigh the advantages of a DSLR - such as price, size, portability, convenience, weight, and even the simple P&S style output that tends to be more 'pop' without as much processing.
Again, not trying to discourage you from a DSLR - if you shoot action, sports, wildlife, low light/high ISO, etc the DSLR will be by far the better tool. What I usually advise people is to consider the majority of what you think you'll be shooting, and lean towards that as the motivator for what to buy. I spent 5 years with advanced prosumers & ultrazooms and did fine, until wildlife & high ISO photography became more than 50% of my overall shooting - at that point, I knew going to a DSLR and accepting the compromises of weight and size were worth it for what I would gain in focus speed, tracking, low light, and maximum versatility in buying myriad lenses for specific types of shooting.
Sony DSLR-A68 / Sony 18-250mm / Minolta 50mm F1.7 / Tamron 150-600mm / Minolta 300mm F4 APO
Sony A6300 / 18-55mm F3.5-5.6 / 55-210mm F4-6.3 / 10-18mm F4 / 35mm F1.8 / 16mm F2.8 / FE70-200mm F4 G OSS / FE70-300mm F4.5-5.6 G OSS / via manual adapter, lots of Pentax K mount, Konica K/AR mount, and Leica M mount manual lenses