I am also attempting to get into a program, so I may not offer the wisest advice, but I can tell you my own strategy - Get in and get out anywhere that will take you. To me it is all about the "foot in the door" thing. IUPUI is not the only school with hundreds of great potential nurses knocking down their door. To answer part of your question, no, I do not think it is (much) less competitive in Spring entry at IUPUI. Unfortunately the system is set up so that the hundreds who do not get into the program in the Fall can tweak their application in their favor (potentially putting them over you) and try again in the next entry class. I say "unfortunately" because this means there is no break for the weary. Institutions will turn down hundreds of people in every program in every semester in most nursing schools in the state.
Again, I believe your Plan B should be to apply and go anywhere that will take you. A good thing about nursing is that once you get some education, you can have your employer pay for the rest of your schooling with educational benefits. This means there are many students who want to become a well-educated RN but are applying to LPN and ASN programs so they can get a job and have their employers finance their RN, BSN and even MSN programs. While some applicants are waiting and taking out student loans, some practicing nurses will be taking out car and home loans. I've been among a pool of other academically talented individuals fighting tooth and nail to get into a program and I've been at it for 2 years at this point. I would feel lucky to get into any program that would take me, no matter what choice on my list it was.
I said above to "get out" quickly because of the inevitable problems that arise from young people (sorry, didn't mean to assume you were young) in a society of underfunded education in an economic climate that requires a college education. You can never know what personal trials lie before you and, as many people on this forum can attest, many people who fight so hard to get into a program do not come out the other side a graduate. I would consider shorter options because 2 years of an ASN program, which gives you a degree, is better than 2 years (or even 3 years) of a BSN program that does not prepare you to sit for the NCLEX-RN. 2 years and a degree is much better than 3 years with nothing to show for all your hard work you paid so much for. Of course I'd apply for the RN if that is what your eventual goal is, but I wouldn't get rejected from the program twice without applying to other programs. By the time you wait to get in at IUPUI, you may have been able to finish at Ivy Tech (and vice versa).
I was attempting the Ivy Tech route for 1.5 years when it became apparent that it was not working for me as quickly as I had planned. I expanded my search at the advice of other students.
The finds of my search: I believe that Marian's program is very similar to IUPUI as far as transfer credits go. I was also told by Marian students not to be intimidated by the high costs of attending this private school because the Financial Aid department is crazy good at helping you get a help (especially if you are a young mother). Ivy Tech has a good enough transfer system, especially considering that is what they, as a community college system, were designed for - transferring credits to finish a bachelors degree. The only quirk I know of is the differing credit hours for anatomy and physiology. (you need to do all of your anatomy and physiology at one school for best results)
In the end, for me, I was close enough to a bachelors degree that I could quickly get a general studies degree at IUPUI and expand my search because I am now also eligible for accelerated programs. If I lived in Cincinnati, for example, I would be eligible for their accelerated MSN programs as well! I decided that 3 years to get 2 bachelors degrees was a better Plan B for me than 3 years to wait to get into and finish the associates degree program at Ivy Tech. I had prior college credits to my advantage, though. The cool thing for me and the accelerated program is that Clarian just gave 'em a million dollars to expand the entry classes and provide scholarships to students who would work at Clarian post-graduation. There are much fewer applications to the accelerated program entries (they may accept around 1/2 of the applicants but it is hard to know since it is expanding so quickly right now), which is why I decided to attempt that option as well.
You may also want to consider using any youth you may have to your advantage. If you are ready and adventurous, there are always fleeting stories of nurse shortages so bad that they welcome students from other areas. When I explored IUPUI in the Summer of 2006, my academic advisor sent me an email forward from a DC hospital that would pay to move, house, and educate you in return for hard work. It probably isn't the best hospital but I would have taken it if I did not have household ties back here in Indy. I also recently read online that Louisiana is looking to cut it's news-making nurse shortage by providing tuition to any qualified student who would move down there to attend. I also just read a list (I'm not sure how updated) on places in the country without a wait for nursing programs like we have here in Indiana.
Keep your chin up! As I heard 2 years ago from the program meeting at Ivy Tech, "sometimes getting a degree in college is all about jumping through the hoops - The only people who get the piece of paper at the end are the ones who show they want it bad enough to jump through all of the hoops the schools put in front of them." I say, "Bring it on!"